Leakage Rate Research Articles

Strategy optimization for the combined procedure of left atrial appendage occlusion plus catheter ablation in patients with atrial fibrillation (COMBINATION): a multi-center, randomized study

Abstract Background The long-term efficacy and safety of combining left atrial appendage closure (LAAC) plus catheter ablation (CA) in patients with atrial fibrillation (AF) in a single procedure have been established. However, the optimal combining strategy has not been well elucidated. Objective To determine the impact of different combining strategies on long-term clinical outcomes. Methods In this prospective multicenter study, patients with non-valvular AF referred for the combining procedure were randomly assigned to the ablation-first or occlusion-first groups at a 1:1 ratio. We evaluated the outcomes of LAAC with a Watchman device and CA using a contact-force sensing catheter during long-term follow-up. Results Of the 202 randomized patients, 194(96.0%) completed the trial with 97 patients in each group. Baseline characteristics were comparable between groups. All procedures were accomplished with acute successful LAAC and restoration of sinus rhythm. Incidences of periprocedural complications were similar. Higher chronic peri-device leak (PDL, 15.5% vs 5.2%, P=0.031) and device-related thrombus (DRT, 8.2% vs 1.0%, P=0.035) rates were observed in the ablation-first group. The event-free survival rate of the primary endpoint (composite of stroke/transient ischemic attack, thromboembolism, clinically-relevant bleeding, cardiovascular rehospitalization/death) was significantly higher in the occlusion-first group (83.5% vs 71.1%, log-rank P=0.036, HR 0.53, 95%CI 0.29-0.95) during a median 2.5-year follow-up. Patients with male gender and higher CHA2DS2-VASc score were at lower risk in the subgroup analysis. Long-term freedoms from AF (77.3% vs 63.5%, log-rank P=0.039) and atrial tachyarrhythmias (70.1% vs 55.7%, log-rank P=0.044) were higher in the occlusion-first group, respectively. Conclusions The occlusion-first approach is recommended for combined procedures where a plug-like device is implanted due to its superior long-term clinical benefits.Flowchart of the COMBINATION trialIncidences of primary endpoint

Extended Prophylactic Antibiotics in Penetrating Neck Aerodigestive Injuries Are Not Associated with Improved Outcomes.

Background: Literature currently supports the limited use of prophylactic antibiotics within the trauma population. However, data supporting limited (≤24 h) or extended (>24 h) use in penetrating aerodigestive neck injuries is lacking. We sought to describe the role of prophylactic antibiotics in this population and hypothesized there was no reduction in complications for patients on extended prophylactic antibiotics. Methods: Using a single-center trauma registry, patients with penetrating aerodigestive neck injuries were identified over a 5-year period. Demographics, injuries, management, and prophylactic antibiotic utilization were collected. Patients were stratified by the utilization of extended prophylactic antibiotics. Outcomes included infection, leak, reinterventions, and mortality. Results: Of 436 patients with penetrating neck injuries, 72 (17%) patients were identified with aerodigestive injuries. Forty-one (57%) patients received extended (>24 h) prophylactic antibiotics, whereas 31 (43%) received limited (≤24 h) prophylactic antibiotics. There was no difference in the patient demographics or injury severity score between the two groups. Extended prophylactic antibiotic use was associated with higher rates of infection (22% vs. 3%, p = 0.036) and leak (15% vs. 0%, p = 0.034) and no difference in reintervention (20% vs. 3%, p = 0.068) or mortality (10% vs. 13%, p = 0.719) compared with limited prophylactic antibiotics. Median duration of extended antibiotic use was 7 days. Operative intervention was equivalent across extended prophylactic antibiotics and limited antibiotics groups (59% vs. 58%, p = 0.968). Conclusions: There is insufficient evidence to support the extended (>24 h) use of prophylactic antibiotics in patients with penetrating neck aerodigestive injuries.

Enhanced Safety and Efficacy of O-Arm Navigation Over C-Arm Guidance in Percutaneous Kyphoplasty for Patients With Osteoporotic Vertebral Compression Fractures and Spinal Deformity: A Comparative Study.

Although percutaneous kyphoplasty (PKP) under C-arm guidance is an effective treatment for osteoporotic vertebral compression fractures (OVCF), obtaining high-definition images in patients with OVCF and spinal deformities can be challenging or insufficient using traditional C-arm guidance, prompting our institution to adopt the O-arm navigation system-which offers comprehensive 3D imaging and precise navigation-and this study compares its safety and efficacy with conventional C-arm-assisted PKP. This was a retrospective study. From February 2019 to February 2022, we enrolled 28 patients with OVCF (44 vertebrae) with spinal deformity treated with O-arm navigation-assisted PKP and 30 patients with OVCF (42 vertebrae) with spinal deformity treated with C-arm-guided PKP. We recorded puncture times, single-segment operation time, number of cases with bone cement leakage, and length of stay. The visual analog scales (VASs), Oswestry disability indexes (ODIs), recovery of Cobbs angle, and vertebral height were used to assess treatment effect before the operation, on the first day postoperation, the first month postoperation, and at the final follow-up. The chi-squared test was utilized for comparing discrete variables, an independent samples t-test was used for continuous variables, and Pearson's chi-squared test and Fisher's exact test were applied for categorical data. Demographic features were comparable between the groups. The O-arm navigation group showed a significant reduction in puncture adjustment per vertebrae, single-segment operation time, and the rate of trocar needle malposition compared to the C-arm guidance group. The rate of cement leakage was decreased in the O-arm-guided PKP group, and other complications did not differ between the two groups. Intragroup comparisons revealed significant improvements in VAS scores and ODI on the first day, first month, and final follow-up after the operation (p < 0.05). The VAS score was significantly lower in the O-arm navigation-assisted PKP group than in the C-arm-guided PKP group on the first day postoperatively (p = 0.049). However, no significant differences in VAS scores were observed between the groups at the first month postoperatively or at the final follow-up. In each follow-up period, there was no significant difference in ODI, Cobb angle, and the percent of anterior vertebral height (AVH %) between the groups. O-arm navigation-assisted PKP demonstrates better clinical safety and efficacy than C-arm-guided PKP, marking it as a minimally invasive, safe, and effective procedure for treating patients with OVCF with spinal deformity.

Prevalence and Impact of Constipation on Reconstructive Outcomes Following Endoscopic Skull Base Surgery

Abstract Objective Postoperative constipation in endoscopic skull base surgery (ESBS) may provoke undesired straining, which, in theory, may create intracranial pressure shifts and impact skull base reconstruction. The purpose of this study is to assess the prevalence and contributing factors to postoperative constipation after ESBS, and whether this impacts reconstructive outcomes. Methods Patients undergoing ESBS between July 2018 and December 2022 at a single-center, tertiary academic skull base surgery program were retrospectively reviewed. Chart reviews were performed to identify average bowel movements per day, indication for surgery, age, sex, body mass index (BMI), history of chronic pain, length of postoperative bedrest, length of stay (LOS), and postoperative use of opioid analgesics. Additionally, use of a standing stool bowel regimen, as-needed (PRN) stool softeners/laxatives, and enemas were recorded. Constipation was defined as greater than 48 hours without a bowel movement. Results In total, 213 patients (115 with intradural pathologies) were identified, of which 146 (69%) patients had postoperative constipation. Postoperative constipation was associated with longer bedrest (1.86 ± 0.20 vs. 1.06 ± 0.12 days; p = 0.011); increased morphine equivalent dose (MED) during postoperative days 2, 3, 5, and 6 (all p &lt; 0.05); and total postoperative MED (106.70 ± 14.01 vs. 46.88 ± 8.44 mg; p &lt; 0.001). Additionally, postoperative constipation was an independent predictor of LOS (p = 0.009). There were no differences in postoperative cerebrospinal fluid (CSF) leak between the groups (p = 0.622). Conclusion Postoperative constipation rates were high after ESBS and likely causative factors include increased immobilization and postoperative opioid use. Standing bowel regimens should be considered in ESBS patients. However, there was no increased rate of postoperative CSF leaks.

Minimally Invasive Transhiatal Esophagectomy Using Antegrade Inversion Technique in Esophageal Cancer: 10-Year Experience from a Tertiary Care Center.

Background: Esophageal cancer surgery aims for curative intent but carries high complication rates. Transthoracic esophagectomy is the dominant approach, however, transhiatal esophagectomy (THE) offers selective advantages in certain clinical scenarios. Minimally invasive THE (MI-THE) is an evolving technique with limited data. Methods: This retrospective study reviewed 38 patients with esophageal cancer who underwent MI-THE using "Antegrade Inversion Technique" between 2013 and 2023 at a tertiary care center. Perioperative outcomes were analyzed. Data were presented as mean with standard deviation, median with interquartile range, and percentages. Results: Most patients (86.8%) had early-stage cancer. Median operative time was 375 minutes, hospital stay was 8 days, and intensive care unit stay was 3 days. All patients achieved a negative resection margin. Pleural effusion (57.9%) was the most common complication, followed by pneumothorax (31.6%) and surgical site infection (15.8%). Anastomotic leak rate was 13.2%. There was no mortality. Conclusions: MI-THE appears safe and feasible with encouraging perioperative outcomes, particularly for early-stage disease and high-risk patients. While potentially offering advantages over open THE, further research is needed to definitively establish its role compared to traditional approaches.

Combustion efficiency analysis and thermal radiation risk quantification for spill fire in sealed ship cabin

In this study, the authors conducted a series of one-dimensional spill fire experiments in a sealed model-scale ship cabin with different leakage rates to reveal the combustion characteristics. The results showed that a stable combustion stage with a consistent combustion area and flame height appears around the cut-off of the fuel, where the consumption of oxygen increases when the leakage rate increases. And the CO2 concentration increases more rapidly and the upward trend is found to appear earlier. Compared with the film thickness in the open space, that of the spill fire in the sealed ship cabin is slightly thinner because of the ventilation control effect. Using the “oxygen-consumption” method, the η of this stage was calculated and verified with the “mass loss rate” method. With these two methods, the HRR of spill fie when burning steadily is calculated. This work also improved the predicting model for the flame height of rectangular pool fire and developed a predicting model for the flame height of a steadily burning spill fire. The error is 14.35 %. Additionally, a predictive model of thermal radiation risk in ship spill fire is developed, and the death risk and unacceptable risk areas are delimited.

Impact of Surgeon Specialization on Outcomes in Emergency Colorectal Surgery: A Systematic Review and Meta-Analysis.

Colorectal emergencies represent a large proportion of acute general surgical workload and carry significant mortality. Identify the influence of surgeon specialization on mortality and other outcomes in emergency colorectal surgery. Systematic searches of Ovid MEDLINE, Ovid EMBASE, and Cochrane electronic databases were performed for studies published from 1 January 1990 to 27 August 2023. Studies were included investigating outcomes in emergency colorectal surgery for adults, comparing colorectal against non-colorectal surgeon specialization. Exclusion criteria were: (1) publications studying primarily pediatric populations; (2) studies incorporating patients who had undergone surgery prior to 1990; (3) studies only published in abstract form or non-English language. Primary outcomes were 30-day mortality and in-hospital mortality. Secondary outcomes were rates of anastomotic leak, reintervention, primary anastomosis, and laparoscopic approach. Of 7676 studies identified, 155 were selected for full-text review and 21 studies were included for quantitative analysis. Eleven studies showed improved 30-day (OR 0.64, 95% CI 0.60-0.68, p < 0.0001) and in hospital mortality (OR 0.66, 95% CI 0.49-0.89, p = 0.007) with colorectal specialization. There was a significantly higher rate of primary anastomosis (OR 2.95, 95% CI 2.02-4.31, p < 0.0001) and use of laparoscopic surgery (OR 2.38, 95% CI 1.42-4.00, p = 0.001) amongst specialized colorectal surgeons. Specialization was also associated with a significant reduction in any stoma formation (OR 0.52, 95% CI 0.28-0.98, p = 0.04). No significant difference was observed for anastomotic leak (OR 0.70, 95% CI 0.45-1.07, p = 0.10) or reintervention rates (OR 0.78, 95% CI 0.55-1.10, p = 0.16). Heterogeneity exists within the included patient populations and definitions of colorectal specialization observed in different countries. Emergency colorectal surgery undertaken by specialized colorectal surgeons is associated with significantly improved post-operative mortality, lower rates of stoma formation and increased rates of primary anastomosis and minimally invasive surgery. CRD42022300541.

Indocyanine Green Fluorescence Angiography (ICG-FA) in the management of intestinal injuries following penetrating abdominal trauma: a case-control study comparing postoperative outcomes.

The surgical management of penetrating hollow visceral injuries includes primary repair or exteriorization. Tissue perfusion at the site of gastrointestinal suture repair may be challenging to assess and is vulnerable to local energy transfer-related injury, micro- or macro-circulatory insufficiency, or splanchnic vasoconstriction for various reasons. Breakdown of suture lines can lead to potentially life-threatening complications. The intraoperative use of Indocyanine Green Fluorescence Angiography (ICG-FA) may reduce the risk of postoperative morbidity and mortality by ensuring optimal tissue perfusion at the chosen site of suture repair. We conducted a retrospective review of the postoperative complications, length of Intensive Care (ICU) stay, and length of hospital stay in patients undergoing laparotomy, with and without ICG-FA for penetrating abdominal trauma at a Level One Trauma Center in Cape Town, South Africa. One hundred patients were included in the study, of which 20 underwent laparotomy with ICG-FA, and 80 did not. The overall complication rate was significantly lower in the ICG-FA group (OR 0.336, p-value=0.0412). The anastomotic leak rates in the ICG-FA and control groups were 0% and 6.25%, respectively (p-value=0.5799). Revision surgery was required in 2 and 14 patients in the ICG-FA and control groups, respectively (OR 0.524, p-value=0.516). The mean length of stay in hospital showed no statistical difference, 8.6 and 5.3 days for the ICG-FA and control groups, respectively (p-value=0.092). The mean length of ICU stay was 6.3 and 2.3 days for the ICG-FA and control groups, respectively (p-value=0.1642). Lower levels of overall postoperative complications and lower rates of revision surgery in patients undergoing laparotomy with ICG-FA are promising. Non-significant findings regarding the relationship between the usage of ICG-FA and anastomotic leak rates suggest the need for larger randomized studies.

Improved catalytic stability of immobilized Candida antarctica lipase B on macroporous resin with organic polymer coating for biodiesel production.

Lipase is one of the most widely studied and applied biocatalysts. Due to the high enzyme leakage rate of the immobilization method of physical adsorption, we propose a new lipase immobilization method, based on the combination of macroporous resin adsorption and organic polymer coating. The immobilized Candida antarctica lipase B (CALB@resin-CAB) was prepared by combining the macroporous resin adsorption with cellulose acetate butyrate coating, and its structure was characterized by various analytic methods. Immobilized lipase was applied for biodiesel production using acidified palm oil as the starting material, the conversion rate achieved as high as 98.5% in two steps. Furthermore, the immobilized lipase displayed satisfactory stability and reusability in biodiesel production. When the aforementioned reaction was carried out in a continuous flow packed bed system, the yield of biodiesel was 94.8% and space-time yield was 2.88g/(mL∙h). The immobilized lipase CALB@resin-CAB showed high catalytic activity and stability, which has good potential for industrial application in the field of oil processing.

Towards more realistic stochastic modelling of leakage in water distribution systems

ABSTRACT A new stochastic model is developed to predict leak types and sizes in water distribution systems. By linking records of actual failures in water networks with new tools for stochastic modelling, the study provides more accurate estimates of network leakage behaviour. District metered areas (DMAs) have been adopted internationally as best practice for monitoring and controlling leakage, with the infrastructure leakage index (ILI) as the main performance indicator. The leakage exponent (N1), which quantifies the relationship between leakage rate and pressure, is a key parameter in describing DMA leakage behaviour. After analysing thousands of stochastic networks for different combinations of pipe material and ILI, the study found that different pipe materials have distinct leakage exponent distributions. Iron and asbestos cement (AC) pipes display N1 values close to 0.5, polyvinyl chloride (PVC) pipes have the highest N1 values, and polyethylene (PE) lies between PVC and iron/AC. The study further showed that current guidelines linking ILI to N1 for different pipe materials depart substantially from the observed results, indicating that these guidelines may need to be updated. The study provides a tool for more realistic modelling of leakage that offers valuable insights into the behaviour of leakage in different pipe materials.

Clinical Effect of Percutaneous Kyphoplasty and Percutaneous Vertebroplasty in Managing Osteoporotic Vertebral Compression Fractures: A Single-Center Propensity Score-Matched Study.

This study aims to evaluate the clinical effectiveness of percutaneous vertebroplasty (PVP) and percutaneous kyphoplasty (PKP) in managing osteoporotic vertebral compression fractures (OVCFs). This retrospective study included 268 elderly OVCF individuals, and 144 individuals were selected after propensity score matching. General patient information, perioperative conditions, vertebral height and Cobb angle, lumbar spinal function, degree of pain, incidence of complications, and fracture recurrence rates were compared and analyzed for the patients. The PKP group exhibited longer surgical duration, greater intraoperative blood loss, and more frequent X-ray fluoroscopy during the perioperative period compared to the PVP group (p < 0.05). However, there was no significant difference in the length of hospital stay between the two groups. Furthermore, PKP surgery significantly improved vertebral height, corrected spinal posture, and enhanced lumbar spinal function while mitigating pain levels within the 12-month postoperative period (p < 0.05). Additionally, the PKP group showed substantially lower rates of bone cement leakage, nerve injury, and fracture recurrence than the PVP group (p < 0.05). Compared to PVP, PKP demonstrates better clinical effectiveness with lower incidence of complications in managing OVCF. However, surgical time and intraoperative trauma should be considered.

Investigation on preparation and properties of gel type 188W/188Re generator

As one of the most important integrated nuclides for diagnosis and treatment in recent years, rhenium-188 (188Re) has a broad scope in the clinical application. Due to the specific properties of such radionuclide, it was mainly provided by the chromatographic 188W-188Re generators. There is no doubt that the application of 188Re in the treatment of various diseases depended on the development of 188W-188Re generator. Considering the high standards of such technology on radioactive activity of 188W and impurity content, a 188W-188Re generator filled with the zirconium tungstate gel has been prepared in this work. The effects of molar ratio of chemical agents, pH, reaction temperature, drying methods, rinsing methods and other conditions on the synthesis of gel particles have been studied. Furthermore, a variety of characterization techniques were used to observe the macro-/micro-morphology and chemical structure of gel particles. It can be concluded that vacuum freeze-dried method could significantly increase the specific surface area, pore size and tungsten content of gel particle. In order to decrease the content of 188W in the elute, a handful of acidic alumina was filled in the bottom of our 188W-188Re generator, an elution and purification integrated-generator was formed. During the first five processes, the nuclear purity of 188Re solution was above 99.99%, the radiochemical purity was approximately 99.5%, the pH value was 5.0–7.0 and the average elution efficiency reached up to 82.7%. In addition, the leakage rate of 188W was low as 1.60 × 10−6, and the peak of elute curve was located at 2 mL without the trailing phenomenon. This work lays a solid foundation for the domestic demand of daughter nuclide 188Re, further makes an outstanding contribution to the application of the radiation therapy technology and the protection of people's health.

Robotic Versus Laparoscopic Gastrectomy for Gastric Cancer: The Largest Systematic Reviews of 68,755 Patients and Meta-analysis.

This meta-analysis aimed to compare the efficacy of robotic gastrectomy (RG) and laparoscopic gastrectomy (LG) in treating gastric cancer (GC). A comprehensive literature search across PubMed, MEDLINE, and Web of Science identified 86 eligible studies, including 68,755 patients (20,894 in the RG group and 47,861 in the LG group). The analysis revealed that RG was associated with superior outcomes in several areas: more lymph nodes were harvested, intraoperative blood loss was reduced, postoperative hospital stays were shorter, and the time to first flatus and oral intake was shortened (all p<0.001). Additionally, RG resulted in lower incidences of conversion to open surgery (OR=0.62, p=0.004), reoperation (OR=0.68, p=0.010), overall postoperative complications (OR=0.82, p<0.001), severe complications (OR=0.65, p<0.001), and pancreatic complications (OR=0.60, p=0.004). However, RG had longer operative times and higher costs (both p<0.001). No significant differences were found between RG and LG in terms of resection margin distance, mortality, anastomotic leakage, or recurrence rates. RG is a safe and effective surgical option for patients of GC, but further improvements in operative duration and costs are needed.

Air Leakages at Microvalves: Pressure Decay Measurements and Extended Continuum Modelling of Knudsen Flows

To improve the performance of valves in relation to the leakage rate, a comprehensive evaluation of the valve characteristics and behavior during pressure exposure is important. Often, these low gas flow rates below 0.1 cm3/min cannot be accurately measured with conventional flow sensors. This paper presents a small and low-cost test rig for measuring gas leakage rates accurately, even far below 0.1 cm3/min, with the pressure decay method. These leakage flows are substantiated with a flow model, where we demonstrate the feasibility of modeling those gas flows with an extended Navier–Stokes framework to obtain more accurate theoretical predictions. As expected, the comparison to the experimental results proves that the classical Navier–Stokes system is unsuitable for modeling Knudsen flows. Hence, self-diffusion of gas, a wall-slip boundary condition, and an effective mean free path model were introduced in a physically evident manner. In terms of the calculated mass flow, while self-diffusion and slip boundary conditions explain deviations from the classical Navier–Stokes equation for Knudsen numbers already smaller than 1, the effective mean free path model has an effect, especially when Kn &gt; 1. For simplified conditions, an analytical solution was presented and compared to the results of an OpenFOAM CFD-solver for flow rates through more complex gap-flow geometries of the flap valve. Hereby, acceptable deviations between 10% and 20% were observed. A comparison with measurement results was carried out. The reproducibility of the measurement method was verified by comparing multiple measurements of one silicon microvalve sample to a state-of-the-art flow sensor. Three geometrically similar passive silicon microvalves were measured with air overpressure decreasing from 15 kPa relative to atmospheric pressure. Maximum gas volume flowing in a blocking direction of 1–26 µL/min with high reproducibility and marginal noise were observed.

Application of low temperature ice saline bone cement in percutaneous vertebroplasty

Percutaneous vertebroplasty uses the traditional method of bone cement filler to inject bone cement, which is easy to solidify, we have found a new method to delay the solidification of bone cement: low temperature ice saline bone cement, which compares the advantages of the new method and the traditional method of injecting bone cement. 82 cases of osteoporotic vertebral compresion fracture(OVCF) were divided into two groups by retrospective study method, 40 patients in group A were treated with the traditional method, 42 patients in group B were treated with the new method.The leakage rate of bone cement, postoperative VAS score, amount of bone cement in each vertebral body, operation time of bone cement, and number of bone cement fillers used were compared between the two groups. There was no significant difference in the bone cement leakage rate, postoperative VAS score, the amount of bone cement in each vertebral body and the number of bone cement fillers used between the two groups; the operation time of bone cement in two groups was statistically significant, and the operation time in group B was significantly longer than that in group A. Low temperature ice saline water bone cement has significant advantages in multiple vertebral fractures, relatively large amount of bone cement injected into each vertebral body and long operation time, which is more suitable for beginners.

Container Plasty in Advanced Painful Osteolytic Vertebral Metastases With Posterior Wall Defect

Study Design: Review of mesh-container plasty (MCP) in osteolytic vertebral metastases. Objective: This study aims to assess the efficacy and safety of MCP in treating advanced vertebral metastases with posterior wall defects. Background: Diagnosis of vertebral metastases typically relies on the patient’s tumor history, bone scans, or vertebral MRI. Surgical intervention often involves sampling vertebral body tissue for pathologic diagnosis. The revised Tokuhashi score is commonly used to predict survival time in patients with bone metastases. Outcome evaluation frequently employs the visual analog scale (VAS) and the Oswestry disability index (ODI) in assessing spinal surgery outcomes. Methods: A retrospective analysis included 111 patients treated between January 2014 and January 2018 in our hospital. Patients were categorized into 2 groups: MCP group (n=51) and PVP group (n=60). Grades based on the percentage of posterior wall defect area were established: grade I (≤25%), grade II (26% to 50%), grade III (51% to 75%), and grade IV (76% to 100%). Efficacy was assessed using VAS and ODI. Results: Both MCP and PVP groups exhibited significant pain relief and improved motor function. No significant differences were observed in VAS and ODI scores at any follow-up point (P&gt;0.05). In the MCP group, bone cement leakage occurred in 13 cases, with a leakage rate of 25.49%. However, none of the patients experienced clinical or neurological symptoms. In the PVP group, bone cement leakage occurred in 50% of patients, with 6 patients developing neurological symptoms. Significant differences between the groups were observed in major complications related to bone cement leakage (P=0.03). Conclusion: MCP demonstrates efficacy in pain relief and safety in treating vertebral metastases with deficient posterior walls. It represents a promising option for spinal surgeons managing vertebral metastases with posterior wall deficiencies.

Numerical Simulation of Hydraulic Fracture Propagation in Unconsolidated Sandstone Reservoirs

In order to comprehensively understand the complex fracture mechanisms in thick and loose sandstone formations, we have carefully developed a coupled finite element numerical model that captures the complex interactions between fluid flow and solid deformation. This model is the cornerstone of our future exploration. Based on this model, the crack propagation problem of hydraulic fracturing under different engineering and geological conditions was studied. In addition, we conducted in-depth research on the key factors that shape the geometry of hydraulic fractures, revealing their subtle differences and complexities. It is worth noting that the sharp contrast between the stress profile and mechanical properties between the production layer and the boundary layer often leads to fascinating phenomena, such as the vertical merging of hydraulic fracture propagation. The convergence of cracks originating from adjacent layers is a recurring theme in these strata. Sensitivity analysis clarified our understanding, revealing that increased elastic modulus promotes longer crack propagation paths. As the elastic modulus increases from 12 GPa to 18 GPa, overall, the maximum crack width slightly decreases, with a less than 10% reduction rate. The increased fluid leakage rate will significantly shorten the length and width of hydraulic fractures (with a maximum decrease of over 70% in fracture width). The increase in viscosity of fracturing fluid causes a change in fracture morphology, with a reduction in length of about 32% and an increase in fracture width of about 25%. It is worth noting that as the leakage rate of fracturing fluid increases, the importance of the viscosity of fracturing fluid decreases relatively. Strategies such as increasing fluid viscosity or adding anti-filtration agents can alleviate these challenges and improve the efficiency of fracturing fluids. In summary, our research findings provide valuable insights that can provide information and optimization for hydraulic fracturing filling and fracturing strategies in loose sandstone formations, promoting more efficient and influential oil and gas extraction work.

Efficacy of lymph node dissection around the inferior mesenteric artery with preservation of the left colic artery for rectal cancer

AbstractObjectiveWe investigated how Japanese D3 dissection with left colic artery (LCA) preservation affects anastomotic leakage after anterior resection with anastomosis for rectal cancer, based on the leak rate. The correlation between LCA preservation, survival, and cancer recurrence after resection was also analyzed.Summary and Background DataIt remains unclear how LCA preservation affects the anastomotic leak rate and oncological outcomes after resection remains unclear. Some reports suggested that anastomotic leakage increases local recurrence and decreases cancer‐specific survival.MethodsIn this study, we enrolled and analyzed 457 patients who underwent radical resection of rectal cancer in the period October 2011 through December 2016. The attending surgeon decided preoperatively and registered whether to preserve the LCA. This trial was registered under the UMIN‐CTR Identifier UMIN000006160.ResultsD3 with LCA preservation was successfully completed in 218 (89.3%) of the 244 patients registered in this group, whereas D3 without LCA preservation was successfully completed in all 213 patients registered in this group. After propensity score matching, the anastomotic leakage rate was 7.86% (11/140) after D3 with LCA preservation and 7.14% (10/140) after D3 without LCA preservation. The overall survival rates were 90.1% and 89.3%, and the recurrence‐free survival rates were 77.6% and 77.3%, respectively.ConclusionsOur findings suggest that LCA preservation has no effect on the incidence of anastomotic leakage after rectal resection with anastomosis using DST and that oncological outcomes may not be affected.

Research on the Dynamic Leaking and Diffusion Law of Hydrogen-Blended Natural Gas under the Soil–Atmosphere Coupled Model

With the breakthrough in mixing hydrogen into natural gas pipelines for urban use, the widespread application of hydrogen-blended natural gas (HBNG) in energy delivery is imminent. However, this development also introduces significant safety concerns due to notable disparities in the physical and chemical properties between methane and hydrogen, heightening the risks associated with gas leaks. Current models that simulate the diffusion of leaked HBNG from buried pipelines into the atmosphere often employ fixed average leakage rates, which do not accurately represent the dynamic nature of gas leakage and diffusion. This study uses computational fluid dynamics (CFD) 2024R1 software to build a three-dimensional simulation model under a soil–atmosphere coupling model for HBNG leakage and diffusion. The findings reveal that, in the soil–atmosphere coupling model, the gas diffusion range under a fixed leakage rate is smaller than that under a dynamic leakage rate. Under the same influencing factors in calm wind conditions, the gas primarily diffuses in the vertical direction, whereas under the same influencing factors in windy conditions, the gas mainly diffuses in the horizontal direction.

Efficacy of endoscopic vacuum therapy in esophageal luminal defects: a systematic review and meta-analysis.

Endoscopic vacuum-assisted closure (EVAC) is a novel technique used to repair esophageal perforation and leaks. Varying data have been reported on the overall success rate of EVAC. We aimed to conduct a metanalysis of the available data on the clinical success rate of EVAC. Electronic databases were searched for publications addressing the efficacy of EVAC in esophageal luminal defects. Pooling was conducted using both fixed and random-effects models. The overall clinical success of EVAC therapy was considered the primary outcome, whereas, overall complication rates, need for adjunct therapy, and mortality were considered secondary outcomes. In total, 366 patients were included in the study. On pooled analysis, the mean age was 66 years with 68.32% of patients being men. Overall pooled clinical success rate of EVAC therapy was 87.95%. Upon subgroup analysis, the pooled clinical success rate of postsurgical anastomotic leak and transmural esophageal perforation were found to be 86.57% and 88.89%, respectively. The all-cause hospital mortality was 14% and 4.2% in patients with esophageal perforation and EVAC, respectively. This study demonstrates that EVAC therapy has a high overall clinical success rate, with low mortality. EVAC therapy seems to be a promising procedure with excellent outcomes in patients with luminal esophageal defects.