scholarly journals On the feasibility of the computational modelling of the endoluminal vacuum-assisted closure of an oesophageal anastomotic leakage

2018 ◽  
Vol 5 (2) ◽  
pp. 171289
Author(s):  
Ester Comellas ◽  
Facundo J. Bellomo ◽  
Iván Rosales ◽  
Luis F. del Castillo ◽  
Ricardo Sánchez ◽  
...  
Keyword(s):  
Anastomotic Leakage ◽  
Computational Analysis ◽  
Treatment Guidelines ◽  
Healing Process ◽  
Computational Modelling ◽  
High Morbidity ◽  
Suction Pressure ◽  
Vacuum Assisted Closure ◽  
Element Analysis ◽  
Basic Characteristics

Endoluminal vacuum-assisted closure (E-VAC) is a promising therapy to treat anastomotic leakages of the oesophagus and bowel which are associated with high morbidity and mortality rates. An open-pore polyurethane foam is introduced into the leakage cavity and connected to a device that applies a suction pressure to accelerate the closure of the defect. Computational analysis of this healing process can advance our understanding of the biomechanical mechanisms at play. To this aim, we use a dual-stage finite-element analysis in which (i) the structural problem addresses the cavity reduction caused by the suction and (ii) a new constitutive formulation models tissue healing via permanent deformations coupled to a stiffness increase. The numerical implementation in an in-house code is described and a qualitative example illustrates the basic characteristics of the model. The computational model successfully reproduces the generic closure of an anastomotic leakage cavity, supporting the hypothesis that suction pressure promotes healing by means of the aforementioned mechanisms. However, the current framework needs to be enriched with empirical data to help advance device designs and treatment guidelines. Nonetheless, this conceptual study confirms that computational analysis can reproduce E-VAC of anastomotic leakages and establishes the bases for better understanding the mechanobiology of anastomotic defect healing.

PS02.147: MANAGEMENT OF A SIMULTANEOUS HIGH ESOPHAGO-TRACHEAL FISTULA CAUSED BY ESOPHAGEAL STENT DUE TO ANASTOMOTIC LEAKAGE AFTER IVOR-LEWIS ESOPHAGECTOMY: A CASE REPORT

2018 ◽  
Vol 31 (Supplement_1) ◽  
pp. 162-162
Author(s):  
Hannah Andrae ◽  
Thomas Musholt ◽  
Hauke Lang ◽  
Peter Grimminger
Keyword(s):  
Case Report ◽  
Anastomotic Leakage ◽  
Healing Process ◽  
Esophageal Stent ◽  
Neoadjuvant Radiochemotherapy ◽  
Carcinoma Of The Esophagus ◽  
Ivor Lewis ◽  
Ivor Lewis Esophagectomy ◽  
First Choice ◽  
Cervical Surgery

Abstract Background Esophagotracheal perforation is a very severe complication. However, an esophagotracheal perforation caused due to an esophageal stent after anastomotic leakage after ivor-lewis resection, is even more complex and associated with high mortality. Therefore we present a case how we managed a high esophagotracheal perforation and anastomotic leakage after ivor-lewis resection of esophageal cancer, prior treated with neoadjuvant radiochemotherapy. Methods Case report A 71-year old patient was transferred to our center due to an esophagotracheal perforation at the proximal stent—and at 18–20 cm from the front teeth row. The stent had been placed due to anastomotic leakage after ivor-lewis resection. The patient's history began with a squamous cell carcinoma of the esophagus, treated with neoadjuvant radiochemotherapy and followed by ivor-lewis esophagectomy. She developed an anastomotic leakage, which was treated with an esophageal stent. This stent perforated and caused a fistula between the esophagus and the trachea. Results After transfer to our center, we performed a tracheotomia with a tubus blocked, distal of the esophagotracheal fistula, to prevent a respiratory insufficiency. We removed the dislocated stent and induced an endosponge therapy. A prolonged healing process lead to a step-by-step decrease of the anastomotic leakage. Finally, the semicircular hole could be supplied by a fibrin sealant. We resected the fistula via cervical surgery and placed a pectoralis muscle flap between trachea and esophagus. The surgery was performed under steady neuromonitoring control. The postoperative course was uncomplicated. The patient could be extubated with spontaneous breathing. Eleven days after surgery, the patient could be discharged fully enteralised. The stomach interponate could be kept. Half a year later, our patient shows up in our regular consultation, reporting no dysphagia. Conclusion Our experience with endosponge treatment suggests that this is the first choice for successful healing of anastomotic leakage after ivor-lewis resection. A stenting of the esophagus after finding an anastomotic leakage can be considered, but is associated with a risk of further complication. Disclosure All authors have declared no conflicts of interest.

Design of an Air-Cooled Radial Turbine: Part 1 — Computational Modelling

2018 ◽  
Author(s):  
Yang Zhang ◽  
Tomasz Duda ◽  
James A. Scobie ◽  
Carl M. Sangan ◽  
Colin D. Copeland ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Experimental Testing ◽  
Temperature Drop ◽  
Computational Modelling ◽  
Operating Conditions ◽  
Inlet Temperature ◽  
Topology Optimisation ◽  
Internal Cooling ◽  
Element Analysis ◽  
Radial Turbine

This paper is part of a two-part publication that aims to design, simulate and test an internally air cooled radial turbine. To achieve this, the additive manufacturing process, Selective Laser Melting (SLM), was utilized to allow internal cooling passages within the blades and hub. This is, to the authors’ knowledge, the first publication in the open literature to demonstrate an SLM manufactured, cooled concept applied to a small radial turbine. In this paper, the internally cooled radial turbine was investigated using a Conjugate Heat Transfer (CHT) numerical simulation. Topology Optimisation was also implemented to understand the areas of the wheel that could be used safely for cooling. In addition, the aerodynamic loss and efficiency of the design was compared to a baseline non-cooled wheel. The experimental work is detailed in Part 2 of this two-part publication. Given that the aim was to test the rotor under representative operating conditions, the material properties were provided by the SLM technology collaborator. The boundary conditions for the numerical simulation were derived from the experimental testing where the inlet temperature was set to 1023 K. A polyhedral unstructured mesh made the meshing of internal coolant plenums including the detailed supporting structures possible. The simulation demonstrated that the highest temperature at the blade leading edge was 117 K lower than the uncooled turbine. The coolant mass flow required by turbine was 2.5% of the mainstream flow to achieve this temperature drop. The inertia of the turbine was also reduced by 20% due to the removal of mass required for the internal coolant plenums. The fluid fields in both the coolant channels and downstream of the cooled rotor were analyzed to determine the aerodynamic influence on the temperature distribution. Furthermore, the solid stress distribution inside the rotor was analyzed using Finite Element Analysis (FEA) coupled with the CFD results.

scholarly journals Characterization of scar tissue biomechanics during adult murine flexor tendon healing

2021 ◽  
Author(s):  
Antonion Korcari ◽  
Alayna E Loiselle ◽  
Mark R Buckley
Keyword(s):  
Mechanical Properties ◽  
Material Properties ◽  
Healing Process ◽  
Tendon Healing ◽  
Scar Tissue ◽  
Element Analysis ◽  
Material Quality ◽  
Treatment Regimens ◽  
Tangent Moduli ◽  
Experimental Findings

Tendon injuries are very common and result in significant impairments in mobility and quality of life. During healing, tendons produce a scar at the injury site, characterized by abundant and disorganized extracellular matrix and by permanent deficits in mechanical integrity compared to healthy tendon. Although a significant amount of work has been done to understand the healing process of tendons and to develop potential therapeutics for tendon regeneration, there is still a significant gap in terms of assessing the direct effects of therapeutics on the functional and material quality specifically of the scar tissue, and thus, on the overall tendon healing process. In this study, we focused on characterizing the mechanical properties of only the scar tissue in flexor digitorum longus (FDL) tendons during the proliferative and remodeling healing phases and comparing these properties with the mechanical properties of the composite healing tissue. Our method was sensitive enough to identify significant differences in structural and material properties between the scar and tendon-scar composite tissues. To account for possible inaccuracies due to the small aspect ratio of scar tissue, we also applied inverse finite element analysis (iFEA) to compute mechanical properties based on simulated tests with accurate specimen geometries and boundary conditions. We found that the scar tissue linear tangent moduli calculated from iFEA were not significantly different from those calculated experimentally at all healing timepoints, validating our experimental findings, and suggesting the assumptions in our experimental calculations were accurate. Taken together, this study first demonstrates that due to the presence of uninjured stubs, testing composite healing tendons without isolating the scar tissue overestimates the material properties of the scar itself. Second, our scar isolation method promises to enable more direct assessment of how different treatment regimens (e.g., cellular ablation, biomechanical and/or biochemical stimuli, tissue engineered scaffolds) affect scar tissue function and material quality in multiple different types of tendons.

scholarly journals Anastomotic leakage following resection of the esophagus – Introduction of an endoscopic scoring system

2020 ◽  
Author(s):  
Jeannine Bachmann ◽  
Marcus Feith ◽  
Christoph Schlag ◽  
Mohamed Abdelhafez ◽  
Marc Martignoni ◽  
...  
Keyword(s):  
Anastomotic Leakage ◽  
Treatment Time ◽  
Malignant Tumors ◽  
Special Focus ◽  
High Morbidity ◽  
Endoscopic View ◽  
University Of Munich ◽  
Tracheobronchial System ◽  
Postoperative Leakage ◽  
Treatment Improvement

Abstract Background Malignant tumors of the esophagus are the sixth leading cause of cancer-related deaths worldwide. Postoperative leakage of the esophago-gastrostomy leads to mediastinal sepsis, which is still associated with a high morbidity and mortality rate. The aim of this study was to describe the endoscopic view of the different severity grades of an anastomotic leakage. MethodsPatients Between June 2016 and September 2018, 144 patients were operated upon in the Department of Surgery, University of Munich, Germany. Among these patients, 34 (23.6%) presented with a leakage of the anastomosis. EndoscopyIn this retrospective analysis the focus is to describe different patterns of leakage of the anastomosis. Results We studied 34 patients in whom post-esophagectomy leakage of the anastomosis was detected and treated with an endoluminal vacuum sponge system. The leakage healed in 26 of 29 patients (success rate 89.7%). With increasing severity of leakage, the treatment time and the in-hospital mortality correspondingly increased. Furthermore, the incidence of development of a fistula to the tracheobronchial system increased with higher grades of leakage. ConclusionsExact descriptions of leakage are necessary to compare the cases and to prove post-treatment improvement. This is, to our knowledge, the first publication to present a leakage grading score in patients after esophagectomy including reconstruction with a gastric tube. This new grading system needs to be tested in further analyses, with special focus on prospective analysis.

Feasibility, Effectiveness, and Safety of Endoscopic Vacuum Therapy for Intrathoracic Anastomotic Leakage Following Transthoracic Esophageal Resection: A Prospective Study

2020 ◽  
Author(s):  
Chengcheng Christine Zhang ◽  
Lukas Liesenfeld ◽  
Rosa Klotz ◽  
Ronald Koschny ◽  
Christian Rupp ◽  
...  
Keyword(s):  
Mortality Rate ◽  
Adverse Events ◽  
Anastomotic Leakage ◽  
Esophageal Resection ◽  
Median Number ◽  
Adverse Event Rate ◽  
Vacuum Therapy ◽  
High Morbidity ◽  
Closure Rate ◽  
Endoscopic Vacuum Therapy

Abstract BackgroundAnastomotic leakage (AL) in the upper gastrointestinal (GI) tract is associated with high morbidity and mortality rates. Especially intrathoracic anastomotic leakage leads to life-threatening adverse events. Endoscopic vacuum therapy (EVT) for anastomotic leakage after transthoracic esophageal resection represents a novel concept. However, sound clinical data are still scarce. This prospective, single-center study aimed to evaluate the feasibility, effectiveness, and safety of EVT for intrathoracic anastomotic leakage following abdomino-thoracic esophageal resection. MethodsFrom March 2014 to September 2019 259 consecutive patients underwent elective transthoracic esophageal resection. 72 patients (27,8 %) suffered from AL. The overall collective in-hospital mortality rate was 3.9% (n=10). Data from those who underwent treatment with EVT were included. ResultsFifty-five patients were treated with EVT. Successful closure was achieved in 89.1% (n=49) by EVT only. The EVT-associated adverse event rate was 5.4% (n=3): bleeding occurred in one patient, while minor sedation-related adverse events were observed in two patients. The median number of EVT procedures per patient was 3. The procedures were performed at intervals of 3-5 days, with a 14-day median duration of therapy. The mortality rate of patients with AL was 7.2% (n=4). Despite successfully terminated EVT, three patients died because of multiple organ failure, acute respiratory distress syndrome, and urosepsis (5.4%). One patient (1.8%) died during EVT due to cardiac arrest. ConclusionsEVT is a safe and effective approach for intrathoracic anastomotic leakages following abdomino-thoracic esophageal resections. It offers a high leakage-closure rate and the potential to lower leakage-related mortalities.

233 POSTOPERATIVE DELIRIUM AFTER OESOPHAGECTOMY FOR CANCER: HOW CAN WE PREVENT AND MANAGE IT?

2020 ◽  
Vol 33 (Supplement_1) ◽  
Author(s):  
A Rita ◽  
E Pinto ◽  
L Pomba ◽  
F Tolin ◽  
G Mattara ◽  
...  
Keyword(s):  
Risk Factors ◽  
Systematic Review ◽  
Literature Search ◽  
Healing Process ◽  
Cochrane Library ◽  
Psychiatric Disease ◽  
High Morbidity ◽  
Systematic Literature Search ◽  
Inclusion Criteria ◽  
Duration Of Surgery

Abstract   Oesophagectomy is associated with high morbidity. One of the postoperative complication observed after esophageal resection is Post Operative Delirium (POD), a psychiatric disease caused by major surgical stress and pharmacological treatments. POD can jeopardize patient healing-process since patients are not collaborative to perioperative care but also because they can harm themselves. Thus the aim of this systematic review was to identify POD factors and its effective management in patients undergone oesophagectomy for oesophageal/oesophagogastric-junction cancer. Methods A comprehensive systematic literature search was conducted using PubMed, Cochrane Library, Scopus, psycINFO and psycARTICLES in order to identify all articles published until January 2020. The following combinations of terms were used for the search strategy: neoplasm; esophagus; gastro-esophageal junction; oesophagectomy; delirium. The following inclusion criteria were set: full article published in English; patients with esophageal cancer undergone oesophagectomy; POD observed. Two researchers independently selected studies matching the inclusion criteria. Duplicate studies, non-relevant topic, data from abstracts or unpublished were excluded. Any disagreements between the researchers’ evaluation concerning inclusion of studies were resolved by consensus. Results Of 235 studies yielded by systematic literature search, 21 met inclusion criteria. POD incidence was observed between 3 and 38% of patients and was precursor of other complications in 1/3 of POD patients. Preoperative risk factors were older age, cerebrovascular disease and pulmonary disfunction. Anxiety and depression resulted predisposing factors. Perioperative risk factors were duration of surgery, ICU length of stay, colloids infusion and blood transfusion. Open-surgery seemed to influence POD more than minimally-invasive and robotic surgery. Interventions identified to treat POD were pharmacological (prophylactic haloperidol, insomnia treatment) and behavioral (patient reorientation by family involvement, bright-light therapy, early mobilization). Conclusion This systematic review identified preoperative, intraoperative and postoperative risk factors of POD after oesophagectomy. No standardized prevention nor treatment of POD was identified. POD impacts patients’ ability in perceiving postoperative symptoms. The difficulty in communicating with health professionals may lead to delay the diagnosis of others complications and prolong hospital stay. Therefore further trials are required to assess efficacy of different POD treatments aimed to enhance postoperative management.

scholarly journals Invasive Cryptococcal Meningitis Presenting as a Skull Base Mass in An Immunocompetent Host: A Case Report

2019 ◽  
Vol 80 (03) ◽  
pp. e31-e35
Author(s):  
Joshua Prickett ◽  
Juan Altafulla ◽  
Anna Knisely ◽  
Zachary Litvack
Keyword(s):  
Skull Base ◽  
Amphotericin B ◽  
Treatment Guidelines ◽  
External Ventricular Drain ◽  
Treatment Algorithm ◽  
Morbidity And Mortality ◽  
Intrathecal Therapy ◽  
High Morbidity ◽  
Fungal Sinusitis ◽  
Immune Systems

Introduction Encephalitis due to Cryptococcus neoformans has been seen almost exclusively in patients with severe compromise of their immune systems, such as acquired immune deficiency syndrome (AIDS). Fungal sinusitis with frank invasion through the cranial base and subsequent seeding of the central nervous system is rare, but should be considered in the differential of patients presenting with meningitis and sinus/skull base lesions even without obvious immune compromise. Improvements in diagnostic testing has increased the ability to correctly identify and new antimicrobials have allowed a condition that once carried a high morbidity and mortality to be managed with better outcomes. We present our treatment algorithm for successful management of an immunocompetent patient with extensive fungal encephalitis due to erosion through the skull base. Case Description The patient is a 59-year-old male presenting unresponsive with sphenoid mass erosive of the skull base and symptoms of meningitis and encephalitis due to C. neoformans. Magnetic resonance imaging (MRI) at presentation demonstrated extensive diencephalic invasion, and a sphenoid mass with erosion of the skull base. Lumbar puncture (LP) confirmed elevated opening pressure of 45 cm H2O, and cultures confirmed infection with C. neoformans. He underwent operative sinonasal debridement followed by placement of an external ventricular drain for management of hydrocephalus. He was treated aggressively with a combination of both intravenous (IV) amphotericin B daily and intrathecal amphotericin B via the ventriculostomy thrice weekly. By the 2nd week of treatment, patient regained consciousness. After 4 weeks of therapy, cerebrospinal fluid (CSF) cultures turned negative, and the external ventricular drain (EVD) was converted to a ventriculoperitoneal shunt (VPS) to manage chronic postinfectious hydrocephalus. We also placed a contralateral Ommaya reservoir to permit continued weekly intrathecal amphotericin B without violation of the shunt valve. With each instillation, the shunt was set to its highest setting to minimize CSF egress for 6 hours then reset to its “drainage” setting. After an additional 6 weeks of outpatient therapy, intrathecal therapy was discontinued. We continued CSF surveillance via Ommaya sampling monthly. At 9-month follow-up, he has remained clinically stable without evidence of recurrent infection. He has residual mild cognitive deficits, but is living semiindependently with his brother. Conclusions Fungal sinusitis is uncommon, especially in those without significantly compromised immune systems. Invasive fungal meningitis resulting in meningitis and encephalitis is even rarer. The condition carries high morbidity and mortality that can only be mitigated with a multidisciplinary effort by neurosurgery, otolaryngology, and infectious disease specialists. While there are no clear treatment guidelines, we present an approach that may permit longer term independent survival.

Finite element analysis (FEA) of polylactic acid/polypropylene carbonate (PLA/PPC) blends fixation plate for craniomaxillofacial surgery

2019 ◽  
Vol 10 (5) ◽  
pp. 678-691
Author(s):  
Intan Najwa Humaira Mohamed Haneef ◽  
Norhashimah Shaffiar ◽  
Yose Fachmi Buys ◽  
Abdul Malek Abd. Hamid
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Human Body ◽  
Healing Process ◽  
Von Mises Stress ◽  
Element Analysis ◽  
Content Type ◽  
New Material ◽  
Fixation Plate ◽  
Von Mises

Purpose The internal fixation plate of bone fractures by using polylactic acid (PLA) has attracted the attention of many researchers, as it is biodegradable and biocompatible to the human body. However, its brittleness has led to implant fracture. On the contrary, polypropylene carbonate (PPC), which is also biodegradable and biocompatible, has an excellent elongation at break. The purpose of this paper is to compare the PLA fixation plate with the new fixation plate made up of PLA/PPC blends by using finite element analysis (FEA). Design/methodology/approach The mandible bone from CT data set and fixation plate was designed by using the MIMICS, Amira and Solidworks softwares. Abaqus software was used for FEA of PLA/PPC fixation plate applied on the fractured mandible bone. A model of mandibular bone with a fracture in the body was subjected to incisor load. The analysis was run to determine the von Mises stress, elongation of the fixation plate and the displacement of the fractured gap of PLA/PPC blends fixation plate. Findings The von Mises stress predicted that all the blend compositions were safe to be used as a fixation plate since the stress values were less than the yield strength. In addition, the stress value of the fixation plate was gradually decreased up to 20 percent when the amount of PPC increased to 30 percent. This indicates that the stress shielding effect was successfully reduced. The elongation of the fixation plate was gradually increased from 11.54 to 12.55 µm as the amount of PPC in the blends increased from 0 to 30 percent, thereby illustrating that the flexibility of the fixation plate was improved by the addition of PPC. Finally, the measured displacement of the fractured gap for all compositions of PLA/PPC blends fixation plate is less than 150 µm, which proves the likely success of fracture fixation by using the PLA/PPC blends. Research limitations/implications An optimum solution of PLA/PPC blends and another new material such as compatibilizer need to be introduced in the blends in order to improve the performance of PLA/PPC blends as a new material for a fixation plate. Besides, by using the same method of producing PLA/PPC blends, longer durations for in vitro degradation of PLA/PPC blends are essential to further understand the degradation behavior of the blends applied in the human body. Finally, it is also important to further test the mechanical strength of PLA/PPC blends during the degradation period to know the current strength of the implant in the healing process of the bone. Practical implications PLA fixation plate and screw can commercially be used in CMF surgery since they reduce cost because of the elimination of secondary surgery to remove the fixation plate and screw after the healing process. Social implications It is hoped that the advantages of this research will ensure the market of PLA product to continue expanding in medical application. Originality/value This study is one of the alternative ways for the biomedical researchers to improve the elongation break of PLA. Currently, many researchers focus on polymeric materials such as PLA, poly(glycolic) acid and polydioxanone blends, which were extensively being used in CMF surgery. However, the work on PLA/PPC blends to be used as one of the materials for the CMF fixation plate is very limited, if any. PPC, the proposed material for this research, will improve the mechanical performance of PLA fixation plate and screw to become more sustainable and flexible when applied on human mandible bone.

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