Endoscopic intramural cystogastrostomy for treatment of peripancreatic fluid collection: A viewpoint from a surgeon

Percutaneous or endoscopic drainage is the initial choice for the treatment of peripancreatic fluid collection in symptomatic patients.Endoscopic transgastric fenestration(ETGF)was first reported for the management of pancreatic pseu-docysts of 20 patients in 2008.From a surgeon’s viewpoint,ETGF is a similar procedure to cystogastrostomy in that they both produce a wide outlet orifice for the drainage of fluid and necrotic debris.ETGF can be performed at least 4 wk after the initial onset of acute pancreatitis and it has a high priority over the surgical approach.However,the surgical approach usually has a better success rate because surgical cystogastrostomy has a wider outlet(>6 cm vs 2 cm)than ETGF.However,percutaneous or endoscopic drainage,ETGF,and surgical approach offer various treatment options for peripancreatic fluid collection patients based on their conditions.

Endoscopic ultrasound-guided pancreatic fluid collection drainage: Where are we?

Pancreatic fluid collections(PFCs)result from injury to the pancreas from acute or chronic pancreatitis,surgery,or trauma.Management of these collections has evolved over the last 2 decades.The choice of interventions includes percu-taneous,endoscopic,minimally invasive surgery,or a combined approach.Endoscopic drainage is the drainage of PFCs by creating an artificial communication between the collection and gastrointestinal lumen that is maintained by placing a stent across the fistulous tract.In this editorial,we endeavored to update the current status of endoscopic ultrasound-guided drainage of PFCs.

Association between acute peripancreatic fluid collections and early readmission in acute pancreatitis:A propensity-matched analysis

BACKGROUND Patients with acute pancreatitis(AP)frequently experience hospital readmissions,posing a significant burden to healthcare systems.Acute peripancreatic fluid collection(APFC)may negatively impact the clinical course of AP.It could worsen symptoms and potentially lead to additional complications.However,clinical evidence regarding the specific association between APFC and early readmission in AP remains scarce.Understanding the link between APFC and readmission may help improve clinical care for AP patients and reduce healthcare costs.AIM To evaluate the association between APFC and 30-day readmission in patients with AP.METHODS This retrospective cohort study is based on the Nationwide Readmission Database for 2016-2019.Patients with a primary diagnosis of AP were identified.Participants were categorized into those with and without APFC.A 1:1 propensity score matching for age,gender,and Elixhauser comorbidities was performed.The primary outcome was early readmission rates.Secondary outcomes included the incidence of inpatient complications and healthcare utilization.Unadjusted analyses used Mann-Whitney U andχ2 tests,while Cox regression models assessed 30-day readmission risks and reported them as adjusted hazard ratios(aHR).Kaplan-Meier curves and log-rank tests verified readmission risks.RESULTS A total of 673059 patients with the principal diagnosis of AP were included.Of these,5.1%had APFC on initial admission.After propensity score matching,each cohort consisted of 33914 patients.Those with APFC showed a higher incidence of inpatient complications,including septic shock(3.1%vs 1.3%,P<0.001),portal venous thrombosis(4.4%vs 0.8%,P<0.001),and mechanical ventilation(1.8%vs 0.9%,P<0.001).The length of stay(LOS)was longer for APFC patients[4(3-7)vs 3(2-5)days,P<0.001],as were hospital charges($29451 vs$24418,P<0.001).For 30-day readmissions,APFC patients had a higher rate(15.7%vs 6.5%,P<0.001)and a longer median readmission LOS(4 vs 3 days,P<0.001).The APFC group also had higher readmission charges($28282 vs$22865,P<0.001).The presence of APFC increased the risk of readmission twofold(aHR 2.52,95%confidence interval:2.40-2.65,P<0.001).The independent risk factors for 30-day readmission included female gender,Elixhauser Comorbidity Index≥3,chronic pulmonary diseases,chronic renal disease,protein-calorie malnutrition,substance use disorder,depression,portal and splenic venous thrombosis,and certain endoscopic procedures.CONCLUSION Developing APFC during index hospitalization for AP is linked to higher readmission rates,more inpatient complications,longer LOS,and increased healthcare costs.Knowing predictors of readmission can help target high-risk patients,reducing healthcare burdens.

Management of pancreatic fluid collections: A comprehensive review of the literature

Pancreatic fluid collections(PFCs) are a frequent complication of pancreatitis. It is important to classify PFCs to guide management. The revised Atlanta criteria classifies PFCs as acute or chronic, with chronic fluid collections subdivided into pseudocysts and walled-off pancreatic necrosis(WOPN). Establishing adequate nutritional support is an essential step in the management of PFCs. Early attempts at oral feeding can be trialed in patients with mild pancreatitis. Enteral feeding should be implemented in patients with moderate to severe pancreatitis. Jejunal feeding remains the preferred route of enteral nutrition. Symptomatic PFCs require drainage; options include surgical, percutaneous, or endoscopic approaches. With the advent of newer and more advanced endoscopic tools and expertise, and an associated reduction in health care costs, minimally invasive endoscopic drainage has become the preferable approach. An endoscopic ultrasonography-guided approach using a seldinger technique is the preferred endoscopic approach. Both plastic stents and metal stents are efficacious and safe; however, metal stents may offer an advantage, especially in infected pseudocysts and in WOPN. Direct endoscopic necrosectomy is often required in WOPN. Lumen apposing metal stents that allow for direct endoscopic necrosectomy and debridement through the stent lumen are preferred in these patients. Endoscopic retrograde cholangio pancreatography with pancreatic duct(PD) exploration should be performed concurrent to PFC drainage. PD disruption is associated with an increased severity of pancreatitis, an increased risk of recurrent attacks of pancreatitis and long-term complications, and a decreased rate of PFC resolution after drainage. Any pancreatic ductal disruption should be bridged with endoscopic stenting.

Pancreatic fluid collections: What is the ideal imaging technique?

Pancreatic fluid collections(PFCs) are seen in up to 50% of cases of acute pancreatitis. The Revised Atlanta classification categorized these collections on the basis of duration of disease and contents, whether liquid alone or a mixture of fluid and necrotic debris. Management of these different types of collections differs because of the variable quantity of debris; while patients with pseudocysts can be drained by straight-forward stent placement, walledoff necrosis requires multi-disciplinary approach. Differentiating these collections on the basis of clinical severity alone is not reliable, so imaging is primarily performed. Contrast-enhanced computed tomography is the commonly used modality for the diagnosis and assessment of proportion of solid contents in PFCs; however with certain limitations such as use of iodinated contrast material especially in renal failure patients and radiation exposure. Magnetic resonance imaging(MRI) performs better than computed tomography(CT) in characterization of pancreatic/peripancreatic fluid collections especially for quantification of solid debris and fat necrosis(seen as fat density globules), and is an alternative in those situations where CT is contraindicated. Also magnetic resonance cholangiopancreatography is highly sensitive for detecting pancreatic duct disruption and choledocholithiasis. Endoscopic ultrasound is an evolving technique with higher reproducibility for fluid-to-debris component estimation with the added advantage of being a single stage procedure for both diagnosis(solid debris delineation) and management(drainage of collection) in the same sitting. Recently role of diffusion weighted MRI and positron emission tomography/CT with ^(18)F-FDG labeled autologous leukocytes is also emerging for detection of infection noninvasively. Comparative studies between these imaging modalities are still limited. However we look forward to a time when this gap in literature will be fulfilled.

Endoscopic ultrasound-guided drainage of pancreatic fluid collections

Pancreatic fluid collections (PFCs) develop secondary to either fluid leakage or liquefaction of pancreatic necrosis following acute pancreatitis, chronic pancreatitis, surgery or abdominal trauma. Pancreatic fluid collections include acute fluid collections, acute and chronic pancreatic pseudocysts, pancreatic abscesses and pancreatic necrosis. Before the introduction of linear endoscopic ultrasound (EUS) in the 1990s and the subsequent development of endoscopic ultrasound-guided drainage (EUS-GD) procedures, the available options for drainage in symptomatic PFCs included surgical drainage, percutaneous drainage using radiological guidance and conventional endoscopic transmural drainage. In recent years, it has gradually been recog-nized that, due to its lower morbidity rate compared to the surgical and percutaneous approaches, endoscopic treatment may be the preferred first-line approach for managing symptomatic PFCs. Endoscopic ultrasound-guided drainage has the following advantages, when compared to other alternatives such as surgical, per-cutaneous and non-EUS-guided endoscopic drainage.EUS-GD is less invasive than surgery and therefore does not require general anesthesia. The morbidity rate is lower, recovery is faster and the costs are lower. EUS-GD can avoid local complications related to per-cutaneous drainage. Because the endoscope is placed adjacent to the fluid collection, it can have direct ac-cess to the fluid cavity, unlike percutaneous drainage which traverses the abdominal wall. Complications such as bleeding, inadvertent puncture of adjacent viscera, secondary infection and prolonged periods of drainage with resultant pancreatico-cutaneous fistulae may be avoided. The only difference between EUS and non-EUS drainage is the initial step, namely, gaining access to the pancreatic fluid collection. All the sub-sequent steps are similar, i.e., insertion of guide-wires with fluoroscopic guidance, balloon dilatation of the cystogastrostomy and insertion of transmural stents or nasocystic catheters. With the introduction of the EUS-scope equipped with a large operative channel which permits drainage of the PFCs in 'one step', EUS-GD has been increasingly carried out in many tertiary care centers and has expanded the safety and efficacy of this modality, allowing access to and drainage of overly challenging fluid collections. However, the nature of the PFCs determines the outcome of this procedure. The technique and review of current literature regarding EUS-GD of PFCs will be discussed.

Endoscopic ultrasound guided drainage of pancreatic fluid collections: Assessment of the procedure, technical details and review of the literature

Endoscopic ultrasound(EUS) guided drainage of pancreatic fluid collections(PFC) has become increasingly popular and become first line management option in many centers. Use of therapeutic echoendoscopes has greatly increased the applicability of EUS guided transmural drainage. Drainage is indicated in symptomatic PFCs, PFC related infection, bleed, luminal obstruction, fistulization and biliary obstruction. EUS guided transmural drainage of PFCs is preferred in patients with non bulging lesions, portal hypertension, bleeding tendency and in those whom conventional drainage has failed. In the present decade significant progress has been made in minimally invasive endoscopic techniques. There are newer stent designs, access devices and techniques for more efficient drainage of PFCs. In this review, we discuss the EUS guided drainage of PFCs in acute pancreatitis.

Endoscopic ultrasound-guided drainage of pancreatic fluid collections: The impact of evolving experience and new technologies in diagnosis and treatment over the last two decades

Background: Endoscopic ultrasound (EUS)-guided drainage is the preferred approach for drainage of pan- creatic uid collections (PFCs) due to the better experience and signi cant progress using newer stents and access devices during last decade. This study aimed to evaluate the role of the evolving experience and possible in uence of new technological devices on the outcome of patients evaluated for PFCs and submitted to EUS-guided drainage during two different periods: the early period at the beginning of experience when a standardized technique was used and the late period when the increased experience of the operator, combined with different stents quality were introduced in the management of PFCs. Methods: We retrospectively analyzed the clinical data of a cohort of 91 consecutive patients, who underwent EUS-guided drainage of symptomatic PFCs from October 2001 to September 2017. Demographic, therapeutic results, complications, and outcomes were compared between early years’ group (2001 2008) and late years’ group (2009 2017). Results: Endoscopic treatment was successfully achieved in 55.6% (20/36) of patients in the early years’ group, and in 96.4% (53/55) in the late years’ group. Eighteen patients (12 in early years’ and 6 in the late year’s group) required additional open surgery. Procedural complications were observed in 5 patients, 4 in early years’ and 1 in late years’ group. Mortality was registered in two patients (2.2%), one for each group. Conclusions: During our long-term survey using EUS-guided endoscopic drainage of PFCs, signi cantly better outcomes in term of improved success rate and decrease complications rate were observed during the late period.

Algorithm for the multidisciplinary management of hemorrhage in EUS-guided drainage for pancreatic fluid collections

Pancreatic fluid collections(PFCs),common sequelae of acute or chronic pancreatitis,are broadly classified as pancreatic pseudocysts or walled-off necrosis according to the revised Atlanta classification.Endoscopic ultrasound(EUS)-guided drainage is often considered a standard first-line therapy preferable to surgical or interventional radiology approaches for patients with symptomatic PFC.EUS-guided drainage is effective and successful;it has a technical success rate of90%-100%and a clinical success rate of 85%-98%.Recent studies have shown a 5%-30%adverse events(AEs)rate for the procedure.The most common AEs include infection,hemorrhage,perforation and stent migration.Hemorrhage,a severe and sometimes deadly outcome,requires a well-organized and appropriate treatment strategy.However,few studies have reported the integrated management of hemorrhage during EUS-guided drainage of PFC.Establishing a practical therapeutic strategy is an essential and significant step in standardized management.The aim of this review is to describe the current situation of EUS-guided drainage of PFCs,including the etiology and treatment of procedure-related bleeding as well as current problems and future perspectives.We propose a novel and meaningful algorithm for systematically managing hemorrhage events.To our limited knowledge,a multidisciplinary algorithm for managing EUS-guided drainage for PFC-related bleeding has not been previously reported.

Lumen apposing metal stents for pancreatic fluid collections:Recognition and management of complications

For patients recovering from acute pancreatitis,the development of a pancreatic fluid collection (PFC) predicts a more complex course of recovery,and introduces difficult management decisions with regard to when,whether,and how the collection should be drained.Most PFCs resolve spontaneously and drainage is indicated only in pseudocysts and walled-off pancreatic necrosis when the collections are causing symptoms and/or local complications such as biliary obstruction.Historical approaches to PFC drainage have included surgical (open or laparoscopic cystgastrostomy or pancreatic debridement),and the placement of percutaneous drains.Endoscopic drainage techniques have emerged in the last several years as the preferred approach for most patients,when local expertise is available.Lumen-apposing metal stents(LAMS) have recently been developed as a tool to facilitate potentially safer and easier endoscopic drainage of pancreatic fluid collections,and less commonly,for other indications,such as gallbladder drainage.Physicians considering LAMS placement must be aware of the complications most commonly associated with LAMS including bleeding,migration,buried stent,stent occlusion,and perforation.Because of the patient complexity associated with severe pancreatitis,management of pancreatic fluid collections can be a complex and multidisciplinary endeavor.Successful and safe use of LAMS for patients with pancreatic fluid collections requires that the endoscopist have a full understanding of the potential complications of LAMS techniques,including how to recognize and manage expected complications.

Electrocautery vs non-electrocautery dilation catheters in endoscopic ultrasonography-guided pancreatic fluid collection drainage

AIM: To investigate the safety and utility of an electrocautery dilation catheter for endoscopic ultrasonography(EUS)-guided pancreatic fluid collection drainage.METHODS: A single-center, exploratory, retrospective study was conducted between August 2010 and August 2014. This study was approved by the Medical Ethics Committee of our institution. Informed, written consent was obtained from each patient prior to the procedure. The subjects included 28 consecutive patients who underwent EUS-guided transmural drainage(EUS-TD) for symptomatic pancreatic and peripancreatic fluid collections(PFCs) by fine needle aspiration using a 19-gauge needle. These patients were retrospectively divided into two groups based on the use of an electrocautery dilation catheter as a fistula dilation device; 15 patients were treated with an electrocautery dilation catheter(electrocautery group), and 13 patients were treated with a non-electrocautery dilation catheter(non-electrocautery group). We evaluated the technical and clinical successes and the adverse events associated with EUS-TD for the treatment of PFCs between the two groups.RESULTS: There were no significant differences in age, sex, type, location and diameter of PFCs between the groups. Thirteen patients(87%) in the electrocauterygroup and 10 patients(77%) in the non-electrocautery group presented with infected PFCs. The technical success rates of EUS-TD for the treatment of PFCs were 100%(15/15) and 100%(13/13) for the electrocautery and the non-electrocautery groups, respectively. The clinical success rates of EUS-TD for the treatment of PFCs were 67%(10/15) and 69%(9/13) for the electrocautery and the non-electrocautery groups, respectively(P = 0.794). The procedure time of EUS-TD for the treatment of PFCs in the electrocautery group was significantly shorter than that of the non-electrocautery group(mean ± SD: 30 ± 12 min vs 52 ± 20 min, P < 0.001). Adverse events associated with EUS-TD for the treatment of PFCs occurred in 0 patients and 1 patient for the electrocautery and the non-electrocautery groups, respectively(P = 0.942).CONCLUSION: EUS-TD using an electrocautery dilation catheter as a fistula dilation device for the treatment of symptomatic PFCs appears safe and contributes to a shorter procedure time.

Endoscopic transgastric fenestration versus percutaneous drainage for management of(peri)pancreatic fluid collections adjacent to gastric wall(with video)

BACKGROUND Percutaneous drainage(PCD)and endoscopic approaches have largely replaced surgical drainage as the initial approach for(peri)pancreatic fluid collections(PFC)s,while complications associated with endoscopic stent implantation are common.AIM To introduce a novel endoscopic therapy named endoscopic transgastric fenestration(ETGF),which involves resection of tissue by endoscopic accessory between gastric and PFCs without stent implantation,and to evaluate its efficacy and safety compared with PCD for the management of PFCs adjacent to the gastric wall.METHODS Patients diagnosed with PFCs adjacent to the gastric wall and who subsequently received ETGF or PCD were restrospectively enrolled.Indications for intervention were consistent with related guidelines.We analyzed patients baseline characteristics,technical and clinical success rate,recurrence and reintervention rate,procedure-related complications and adverse events.RESULTS Seventy-two eligible patients were retrospectively identified(ETGF=34,PCD=38)from October 2017 to May 2021.Patients in the ETGF group had a significantly higher clinical success rate than those in the PCD group(97.1 vs 76.3%,P=0.01).There were no statistically significant differences regarding recurrence,reintervention and incidence of complication between the two groups.While long-term catheter drainage was very common in the PCD group.CONCLUSION Compared with PCD,ETGF has a higher clinical success rate in the management of PFCs adjacent to the gastric wall.ETGF is an alternative effective strategy for the treatment of PFCs adjacent to the gastric wall.

Can ultrasound predict the severity of acute pancreatitis early by observing acute fluid collection?

INTRODUCTIONThe spectrum of acute pancreatitis (AP) ranges from a mild spontaneously resolved disorder to severe disease with mortality up to 20%-48.4%[1-3]. sAP is defined as the AP with organ failure and /or local complications which developed form acute fluid collection (AFC) including necrosis ,abscess , pseudocyst formation into or around the pancreas [4].

Acute pancreatitis:A pictorial review of early pancreatic fluid collections

Acute pancreatitis is a common acute inflammatory disease involving the pancreas and peripancreatic tissues or remote organs.The revised Atlanta classification 2012 of acute pancreatitis divides patients into mild,moderately severe and severe groups.Major changes of the classification include acute fluid collection terminology.However,some inappropriate terms of the radiological diagnosis reports in the daily clinical work or available literature may still be found.The aim of this review article is:to present an image-rich overview of different morphologic characteristics of the early-stage(within 4 wk after symptom onset)local complications associated with acute pancreatitis by computed tomography or magnetic resonance imaging;to clarify confusing imaging concepts for pancreatic fluid collections and underline standardised reporting nomenclature;to assist communication among treating physicians;and to facilitate the implications for clinical management decision-making.

Novel and supplementary management of pancreatic fluid collections:Endoscopic ultrasound-guided drainage

AIM To compare efficacy and safety of endoscopic ultrasound (EUS)-guided and surgical drainage in pancreatic fluid collection management.METHODS Data were obtained retrospectively from January 2012 to December 2016.Patients with pancreatic fluid collection were performed EUS-guided or surgical procedure.Main outcome measures including clinical efficiency,complication,duration of procedures,hospital stay and cost were analyzed.RESULTS Thirty-six patients were enrolled into the study,including 14 in endoscopic group while 22 in the surgical group.Twelve (86%) patients were treated successfully by endoscopic approach while 21 (95%) patients benefited through surgical procedure.Endoscopic treatment had higher recurrence and complication rates than surgery,resulting in more re-interventions.Meanwhile,duration of procedure,hospital stay and cost were significantly lower in endoscopic group.CONCLUSION Both approaches were effective and safe.EUS-guided approach should be the first-line treatment in mild and simple cases,while surgical approach should be considered as priority in severe and complex cases.

Subdural fluid collection rather than meningitis contributes to hydrocephalus after cervical laminoplasty:A case report

BACKGROUND Hydrocephalus following dural tear after spinal surgery is rare.Although a few cases of obstructive hydrocephalus caused by subdural fluid collection and communicating hydrocephalus associated with meningitis have been reported,the mechanism remains uncertain.Herein we describe a patient complicated with hydrocephalus after cervical laminoplasty in whom subdural fluid collection in the cervical spine and posterior cranial fossa rather than chronic meningitis was the main mechanism.CASE SUMMARY A 45-year-old man underwent cervical laminoplasty for cervical spondylotic myelopathy at a local hospital.Ten days postoperatively,a high fever occurred and magnetic resonance imaging(MRI)showed cerebrospinal fluid(CSF)leakage.Pseudomeningocele liquid test showed high levels of protein and white blood cell(WBC)count with negative bacterial culture.The patient was treated with shortterm intravenous antibiotic and discharged with normal body temperature.The patient was uneventful during the first 8 mo follow-up although repeated MRI showed persistent pseudomeningocele.At the 9th mo postoperatively,the patient gradually presented with dizziness and headache accompanied by recurrent weakness of his left arm.Imaging examinations demonstrated hydrocephalus and a cystic lesion around the cervical spinal cord.CSF test from lumbar puncture indicated chronic meningitis.MRI on 1 d after pseudomeningocele drainage showed a significant decrease in the cystic volume,suggesting that the cystic lesion would be subdural fluid collection rather than adhesive arachnoiditis.After dural defect repair,the patient’s symptoms completely resolved and hydrocephalus gradually disappeared.CSF analysis at the 21-mo follow-up revealed significantly decreased protein level and WBC count.CONCLUSION Subdural fluid collection rather than meningitis contributes to the hydrocephalus formation after cervical laminoplasty.

Interventional radiology followed by endoscopic drainage for pancreatic fluid collections associated with high bleeding risk: Two case reports

BACKGROUND Endoscopic ultrasound(EUS)-guided transluminal drainage is an advanced technique used to treat pancreatic fluid collections(PFCs). However, gastric varices and intervening vessels may be associated with a high risk of bleeding and are, therefore, listed as relative contraindications. Herein, we report two patients who underwent interventional embolization before EUS-guided drainage.CASE SUMMARY Two 32-year-old males developed symptomatic PFCs after acute pancreatitis and came to our hospital for further treatment. One patient suffered from intermittent abdominal pain and vomiting, and computed tomography(CT) imaging showed an encapsulated cyst 7.93 cm × 6.13 cm in size. The other patient complained of a mass inside the abdomen, which gradually became enlarged. Gastric varices around the ideal puncture site were detected by EUS when we evaluated the possibility of endoscopic drainage in both patients. Interventional embolization was recommended as the first procedure to decrease the risk of bleeding. After that, EUS-guided transluminal drainage was successfully conducted, without vascular rupture. No postoperative complications occurred during hospitalization, and no recurrence was detected at the last follow-up CT scan performed at 1 mo.CONCLUSION Interventional embolization is a safe, preoperative procedure that is performed before EUS-guided drainage in PFC patients with gastric varices or at high risk of bleeding.

Peripancreatic collections in acute pancreatitis: Correlation between computerized tomography and operative fi ndings

AIM: To evaluate the ability of contrast-enhanced computerized tomography (CECT) to characterize the nature of peripancreatic collections.METHODS: Twenty five patients with peripancreatic collections on CECT and who underwent operative intervention for severe acute pancreatitis were retrospectively studied. The collections were classified into (1) necrosis without frank pus; (2) necrosis with pus; and (3) fluid without necrosis. A blinded radiologist assessed the preoperative CTs of each patient for necrosis and peripancreatic fluid collections. Peripancreatic collections were described in terms of volume, location, number, heterogeneity, fluid attenuation, wall perceptibility, wall enhancement, presence of extraluminal gas, and vascular compromise.RESULTS: Fifty-four collections were identif ied at operation, of which 45 (83%) were identif ied on CECT. Of these, 25/26 (96%) had necrosis without pus, 16/19 (84%) had necrosis with pus, and 4/9 (44%) had fluid without necrosis. Among the study characteristics, fluid heterogeneity was seen in a greater proportion of collections in the group with necrosis and pus, compared to the other two groups (94% vs 48% and 25%, P = 0.002 and 0.003, respectively). Among the wall characteristics, irregularity was seen in a greater proportion of collections in the groups with necrosis with and without pus, when compared to the group with fluid without necrosis (88% and 71% vs 25%, P = 0.06 and P < 0.01, respectively). The combination of heterogeneity and presence of extraluminal gas had a specif icity and positive likelihood ratio of 92% and 5.9, respectively, in detecting pus. CONCLUSION: Most of the peripancreatic collections seen on CECT in patients with severe acute pancreatitis who require operative intervention contain necrotic tissue. CECT has a somewhat limited role in differentiating the different types of collections.

Study of Even ^(230-238)U Isotopes by Using Cranked Nilsson Model,Single Particle Schrodinger Fluid and Collective Model

The Cranking Nilsson model is applied to calculate the single-particle energy eigenvalues and eigenfunctions of nuclei in a strongly deformed potential. Accordingly, The L. D. Energy, the Strutinsky inertia, the L. D. inertia, the volume conservation factor , the smoothed energy, the BCS energy, the G-value and the electric quadrupole moment of the five uranium isotopes: 230U, 232U, 234U, 236U and 238U are calculated as functions of the deformation parameter. Furthermore, the single-particle Schrodinger fluid is applied to calculate the rigid-body model, the cranking-model and the equilibrium-model moments of inertia of the five uranium isotopes. Moreover, the collective model is applied to calculate the rotational energies of these isotopes. The best potential and deformation parameters are also given.

均匀流下两柔性梁纵列行为变化研究

随着水下仿生柔性航行器的蓬勃发展,如何有效地开展集群组织、提升效能成为研究热点之一,特别是当柔性航行器编队遭遇外界环境变化时.基于此,开展流场作用下两个自推进柔性梁纵列行为变化的数值研究,探讨外部流场的影响规律,揭示集群纵列行为适应性和多变性机理.结果表明:横向流下柔性梁速度曲线变化周期增加1倍,幅值增大超过3倍,且出现了波峰、波谷幅值不等的非线性现象,新的纵列结构形成;纵向流对柔性梁运动具有线性影响,其推进速度在顺流/逆流时线性地增加/减少,变化值与流速大小一致,两柔性梁纵列结构与静水中保持一致.对流场细节进行分析可知,外部流场影响了尾流中涡的运动及融合,这是导致纵列聚集结构发生变化的原因.横向流下涡发生融合,对称涡结构被破坏,而纵向流下所有尾涡产生相同水平位移,其对称结构并不发生改变.此外,对比了流场下纵列两柔性梁的推进速度、功率和效率数据,发现最小功率、最大速度和效率并不出现在顺流工况,更大范围流场方向上柔性梁性能较静水中得到提升.以上得到的流场下纵列行为变化研究数据和机理可为水下仿生柔性航行器集群遭遇外部流场时主动选取航行策略提供支撑.