TY - RPRT A1 - Steiger, Tamara A1 - Foltan, Maik A1 - Philipp, Alois A1 - Müller, Thomas A1 - Gruber, Michael Andreas A1 - Bredthauer, Andre A1 - Krenkel, Lars A1 - Birkenmaier, Clemens A1 - Lehle, Karla T1 - Accumulations of von Willebrand factor within ECMO oxygenators: Potential indicator of coagulation abnormalities in critically ill patients? N2 - Clot formation within membrane oxygenators (MOs) remains a critical problem during extracorporeal membrane oxygenation (ECMO). The composition of the clots—in particular, the presence of von Willebrand factor (vWF)—may be an indicator for prevalent nonphysiological flow conditions, foreign body reactions, or coagulation abnormalities in critically ill patients. Mats of interwoven gas exchange fibers from randomly collected MOs (PLS, Maquet, Rastatt, Germany) of 21 patients were stained with antibodies (anti‐vWF and anti‐P‐selectin) and counterstained with 4′,6‐diamidino‐2‐phenylindole. The extent of vWF‐loading was correlated with patient and technical data. While 12 MOs showed low vWF‐loadings, 9 MOs showed high vWF‐loading with highest accumulations close to crossing points of adjacent gas fibers. The presence and the extent of vWF‐fibers/“cobwebs,” leukocytes, platelet–leukocyte aggregates (PLAs), and P‐selectin‐positive platelet aggregates were independent of the extent of vWF‐loading. However, the highly loaded MOs were obtained from patients with a significantly elevated SOFA score, severe thrombocytopenia, and persistent liver dysfunction. The coagulation abnormalities of these critically ill patients may cause an accumulation of the highly thrombogenic and elongated high‐molecular‐weight vWF multimers in the plasma which will be trapped in the MOs during the ECMO therapy. Y1 - 2019 ER - TY - JOUR A1 - Birkenmaier, Clemens A1 - Dornia, Christian A1 - Lehle, Karla A1 - Müller, Thomas A1 - Gruber, Michael Andreas A1 - Philipp, Alois A1 - Krenkel, Lars T1 - Analysis of Thrombotic Deposits in Extracorporeal Membrane Oxygenators by High-resolution Microcomputed Tomography: A Feasibility Study JF - ASAIO Journal / American Society for Artificial Internal Organs N2 - Coagulative disorders, especially clotting during extracorporeal membrane oxygenation, are frequent complications. Direct visualization and analysis of deposits in membrane oxygenators using computed tomography (CT) may provide an insight into the underlying mechanisms causing thrombotic events. However, the already established multidetector CT1 (MDCT) method shows major limitations. Here, we demonstrate the feasibility of applying industrial micro-CT (μCT) to circumvent these restrictions. Three clinically used membrane oxygenators were investigated applying both MDCT and μCT. The scans were analyzed in terms of clot volume and local clot distribution. As validation, the clot volume was also determined from the fluid volume, which could be filled into the respective used oxygenator compared to a new device. In addition, cross-sectional CT images were compared with crosscut oxygenators. Based on the μCT findings, a morphological measure (sphericity) for assessing clot structures in membrane oxygenators is introduced. Furthermore, by comparing MDCT and μCT results, an augmentation of the MDCT method is proposed, which allows for improved clot volume determination in a clinical setting. Y1 - 2020 U6 - https://doi.org/10.1097/MAT.0000000000001089 SN - 1538-943X VL - 66 IS - 8 SP - 922 EP - 928 PB - Lippincott Williams & Wilkins ER - TY - GEN A1 - Birkenmaier, Clemens A1 - Dornia, Christian A1 - Lehle, Karla A1 - Krenkel, Lars T1 - Feasibility of detecting thrombotic deposits in membrane oxygenators using micro computed tomography T2 - 25th Congress of the European Society of Biomechanics, July 7-10, 2019, Vienna, Austria Y1 - 2019 UR - https://esbiomech.org/conference/archive/2019vienna/Contribution_129.pdf ER - TY - GEN A1 - Krenkel, Lars T1 - Maskenpflicht für Aerosole – wie wir medizinisches Personal in der Pandemie schützen T2 - TRIOKON Digital 2021 : Zukunft Ostbayern, 29.09.2021, Weiden, Deutschland KW - Aerosole KW - Pandemie KW - SARS-CoV-2 Y1 - 2021 UR - https://www.youtube.com/watch?v=bYRFpp_Xxvc ER - TY - CHAP A1 - Stelzer, Vera A1 - Tauwald, Sandra Melina A1 - Vielsmeier, Veronika A1 - Cieplik, Fabian A1 - Kandulski, Arne A1 - Schneider-Brachert, Wulf A1 - Wünsch, Olaf A1 - Rütten, Markus A1 - Krenkel, Lars ED - Dillman, Andreas ED - Heller, Gerd ED - Kraemer, Ewald ED - Wagner, Claus ED - Weiss, Julien T1 - Generation and Distribution of Surgical Smoke During High Frequency Electrocauterization T2 - New Results in Numerical and Experimental Fluid Mechanics XIV. STAB/DGLR Symposium 2022 N2 - Surgical Smoke is generated during the cauterization of tissue with high-frequency (HF) devices and consists of 95% water vapor and 5% cellular debris. When the coagulation tweezers, which are supplied with HF voltage by the HF device, touch tissue, the electric circuit is closed, and smoke is generated by the heat. In-vivo investigations are performed during tracheotomies where surgical smoke is produced during coagulation of tissue. Furthermore, in-vitro parametric studies to investigate the particle number and size distribution and the spatial distribution of surgical smoke with laser light sheet technique are conducted. With higher power of the HF device, the particles generated are larger in size and the total number of particles generated is also higher. Adding artificial saliva to the tissue shows even higher particle counts. The study by laser light sheet also confirms this. The resulting characteristic size distribution, which may include viruses and bacterial components, confirms considering the risk arising from surgical smoke. Furthermore, the experiments will provide the database for further numerical investigations. KW - Surgical smoke KW - Fluid Mechanics KW - Aerosols KW - Tracheotomies Y1 - 2023 SN - 978-3-031-40481-8 U6 - https://doi.org/10.1007/978-3-031-40482-5_53 SP - 559 EP - 568 PB - Springer Nature Switzerland AG CY - Cham, Switzerland ER - TY - JOUR A1 - Lingel, Maximilian P. A1 - Haus, Moritz A1 - Paschke, Lukas A1 - Foltan, Maik A1 - Lubnow, Matthias A1 - Gruber, Michael A1 - Krenkel, Lars A1 - Lehle, Karla T1 - Clinical relevance of cell-free DNA during venovenous extracorporeal membrane oxygenation JF - Artificial organs N2 - BACKGROUND: Thrombosis remains a critical complication during venovenous extracorporeal membrane oxygenation (VV ECMO). The involvement of neutrophil extracellular traps (NETs) in thrombogenesis has to be discussed. The aim was to verify NETs in the form of cell-free DNA (cfDNA) in the plasma of patients during ECMO. METHODS: A fluorescent DNA-binding dye (QuantifFluor®, Promega) was used to detect cell-free DNA in plasma samples. cfDNA concentrations from volunteers (n = 21) and patients (n = 9) were compared and correlated with clinical/technical data before/during support, ECMO end and time of a system exchange. RESULTS: Before ECMO, patients with a median (IQR) age of 59 (51/63) years, SOFA score of 11 (10/15), and ECMO run time of 9.0 (7.0/19.5) days presented significantly higher levels of cfDNA compared to volunteers (6.4 (5.8/7.9) ng/μL vs. 5.9 (5.4/6.3) ng/μL; p = 0.044). Within 2 days after ECMO start, cfDNA, inflammatory, and hemolysis parameters remained unchanged, while platelets decreased (p = 0.005). After ECMO removal at the end of therapy, cfDNA, inflammation, and coagulation data (except antithrombin III) remained unchanged. The renewal of a system resulted in known alterations in fibrinogen, d-dimers, and platelets, while cfDNA remained unchanged. CONCLUSION: Detection of cfDNA in plasma of ECMO patients was not an indicator of acute and circuit-induced thrombogenesis. KW - blood KW - cell- free DNA KW - coagulation KW - ECMO KW - inflammation KW - neutrophil extracellular traps Y1 - 2023 U6 - https://doi.org/10.1111/aor.14616 SN - 1525-1594 VL - 47 IS - 11 SP - 1720 EP - 1731 PB - Wiley ER - TY - JOUR A1 - Tauwald, Sandra Melina A1 - Erzinger, Florian A1 - Quadrio, Maurizio A1 - Rütten, Markus A1 - Stemmer, Christian A1 - Krenkel, Lars T1 - Tomo-PIV in a patient-specific model of human nasal cavities: a methodological approach JF - Measurement Science and Technology N2 - The human nose serves as the primary gateway for air entering the respiratory system and plays a vital role in breathing. Nasal breathing difficulties are a significant health concern, leading to substantial healthcare costs for patients. Understanding nasal airflow dynamics is crucial for comprehending respiratory mechanisms. This article presents a detailed study using tomo-Particle Image Velocimetry (PIV) to investigate nasal airflow dynamics while addressing its accuracy. Embedded in the OpenNose project, the work described aims to provide a validation basis for different numerical approaches to upper airway flow. The study includes the manufacturing of a transparent silicone model based on a clinical CT scan, refractive index matching to minimize optical distortions, and precise flow rate adjustments based on physiological breathing cycles. This method allows for spatial high-resolution investigations in different regions of interest within the nasopharynx during various phases of the breathing cycle. The results demonstrate the accuracy of the investigations, enabling detailed analysis of flow structures and gradients. This spatial high-resolution tomo-PIV approach provides valuable insights into the complex flow phenomena occurring during the physiological breathing cycle in the nasopharynx. The study's findings contribute to advancements in non-free-of-sight experimental flow investigation of complex cavities under nearly realistic conditions. Furthermore, reliable and accurate experimental data is crucial for properly validating numerical approaches that compute this patient-specific flow for clinical purposes. Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-70393 N1 - Corresponding author: Sandra Melina Tauwald VL - 35 IS - 5 PB - IOP Publishing ER - TY - JOUR A1 - Tauwald, Sandra Melina A1 - Michel, Johanna A1 - Brandt, Marie A1 - Vielsmeier, Veronika A1 - Stemmer, Christian A1 - Krenkel, Lars T1 - Experimental studies and mathematical modeling of the viscoelastic rheology of tracheobronchial mucus from respiratory healthy patients JF - Multidisciplinary Respiratory Medicine N2 - BACKGROUND: Tracheobronchial mucus plays a crucial role in pulmonary function by providing protection against inhaled pathogens. Due to its composition of water, mucins, and other biomolecules, it has a complex viscoelastic rheological behavior. This interplay of both viscous and elastic properties has not been fully described yet. In this study, we characterize the rheology of human mucus using oscillatory and transient tests. Based on the transient tests, we describe the material behavior of mucus under stress and strain loading by mathematical models. METHODS: Mucus samples were collected from clinically used endotracheal tubes. For rheological characterization, oscillatory amplitude-sweep and frequency-sweep tests, and transient creep-recovery and stress-relaxation tests were performed. The results of the transient test were approximated using the Burgers model, the Weibull distribution, and the six-element Maxwell model. The three-dimensional microstructure of the tracheobronchial mucus was visualized using scanning electron microscope imaging. RESULTS: Amplitude-sweep tests showed storage moduli ranging from 0.1 Pa to 10000 Pa and a median critical strain of 4 %. In frequency-sweep tests, storage and loss moduli increased with frequency, with the median of the storage modulus ranging from 10 Pa to 30 Pa, and the median of the loss modulus from 5 Pa to 14 Pa. The Burgers model approximates the viscoelastic behavior of tracheobronchial mucus during a constant load of stress appropriately (R2 of 0.99), and the Weibull distribution is suitable to predict the recovery of the sample after the removal of this stress (R2 of 0.99). The approximation of the stress-relaxation test data by a six-element Maxwell model shows a larger fit error (R2 of 0.91). CONCLUSIONS: This study provides a detailed description of all process steps of characterizing the rheology of tracheobronchial mucus, including sample collection, microstructure visualization, and rheological investigation. Based on this characterization, we provide mathematical models of the rheological behavior of tracheobronchial mucus. These can now be used to simulate mucus flow in the respiratory system through numerical approaches. KW - tracheobronchial mucus KW - rheological model KW - viscoelasticity Y1 - 2023 U6 - https://doi.org/10.4081/mrm.2023.923 SN - 2049-6958 N1 - Corresponding author: Sandra Melina Tauwald VL - 18 IS - 1 PB - PAGEPress CY - Pavia, Italy ER - TY - CHAP A1 - Tauwald, Sandra Melina A1 - Quadrio, Maurizio A1 - Rütten, Markus A1 - Stemmer, Christian A1 - Krenkel, Lars T1 - High Spatial Resolution Tomo-PIV of the Trachea Focussing on the Physiological Breathing Cycle T2 - New Results in Numerical and Experimental Fluid Mechanics XIV - Contributions to the 23nd STAB/DGLR Symposium N2 - Investigations of complex patient-specific flow in the nasopharynx requires high resolution numerical calculations validated by reliable experiments. When building the validation base and the benchmark of computational fluid dynamics, an experimental setup of the nasal airways was developed. The applied optical measurement technique of tomo-PIV supplies information on the governing flow field in three dimensions. This paper presents tomo-PIV measurements of the highly complex patient-specific geometry of the human trachea. A computertomographic scan of a person’s head builds the basis of the experimental silicone model of the nasal airways. An optimised approach for precise refractive index matching avoids optical distortions even in highly complex non-free-of-sight 3D geometries. A linear-motor-driven pump generates breathing scenarios, based on measured breathing cycles. Adjusting of the CCD cameras‘ double-frame-rate PIV-Δt enables the detailed analysis of flow structures during different cycle phases. Merging regions of interest enables high spatial resolution acquisition of the flow field. KW - Tomographic PIV KW - Flow visualisation KW - Breathing cycle KW - Nasal airflow Y1 - 2023 N1 - Accepted for publication, not yet published PB - Springer ER - TY - CHAP A1 - Fuhrmann, Thomas T1 - Semi-Structured Lab Projects in Communication Engineering Education T2 - 2023 IEEE Global Engineering Education Conference (EDUCON), 01-04 May 2023, Kuwait N2 - It is generally known that project-based learning is a very important part of engineering education to connect theoretical knowledge with practical work. Students learn to apply their knowledge to real-world challenges as it is the case in their later professional life. If students are not used to project work or the scientific topic is new and relatively complex, they may be overwhelmed. The consequence is that students achieve poor results, are frustrated, and therefore learning success is low. Semi-structured projects are introduced that combine the advantages of structured experiments with projects. The project work is structured into several parts with detailed descriptions of the tasks. In the end, students get similar results to doing a free project, but the success rate is higher due to higher guidance. Therefore, these semi-structured projects are seen to be an appropriate method to guide students to learn how to do project work. The feedback from most students is very positive. Some students with no previous lab experience complained about the project work and wished for more guidance to become familiar with lab work. In sum, the student feedback is encouraging to develop semi-structured projects further. KW - Knowledge engineering KW - Task analysis KW - Communication engineering education Y1 - 2023 U6 - https://doi.org/10.1109/EDUCON54358.2023.10125244 SP - 1 EP - 5 PB - IEEE ER - TY - CHAP A1 - Birkenmaier, Clemens A1 - Steiger, Tamara A1 - Philipp, Alois A1 - Lehle, Karla A1 - Krenkel, Lars T1 - Flow-induced accumulations of von Willebrand factor inside oxygenators during extracorporeal life support therapy T2 - Proceedings of 12th International Conference BIOMDLORE 2018, June 28–30, 2018, Białystok, Poland N2 - BACKGROUND: Shear-induced conformational changes of von Willebrand factor (vWF) may be responsible for coagulation disorder and clot formation inside membrane oxygenators (MOs) during extracorporeal membrane oxygenation (ECMO) therapy. OBJECTIVE: The aim was to identify vWF structures inside clinically used MOs and employ computational fluid dynamics to verify the corresponding flow conditions. METHODS: Samples from gas exchange membranes (GEM) from MOs were analysed for accumulations of vWF and P-selectin-positive platelets using immunofluorescence techniques. Streamlines and shear rates of the flow around GEMs were computed using a laminar steady Reynolds-Averaged-Navier-Stokes approach. RESULTS: Most samples were colonized with equally distributed leukocytes, integrated in thin cobweb-like vWF-structures. Only 25 % of the samples showed extended accumulations of vWF. Computed streamlines showed considerable cross flow between interconnected neighbouring channels. Stagnation points were non-symmetric and contact faces were washed around closely. The occurring maximum shear rates ranged from 2,500 to 3,000 1/s. CONCLUSIONS: If pronounced vWF structures are present, shape and extent match the flow computations well. Computed shear rates bear a critical degree of uncertainty due to the improper viscosity model. If flow conditions inside the MO were sufficient to affect vWF, a more consistent distribution of vWF across the samples should be present. KW - Blood Viscosity KW - Shear Rate Induced Coagulation KW - Hemodynamics KW - Membrane Oxygenator KW - von Willebrand factor Y1 - 2018 SN - 978-1-5386-2396-1 U6 - https://doi.org/10.1109/BIOMDLORE.2018.8467205 PB - IEEE CY - Piscataway, NJ ER - TY - JOUR A1 - Steiger, Tamara A1 - Foltan, Maik A1 - Philipp, Alois A1 - Mueller, Thomas A1 - Gruber, Michael Andreas A1 - Bredthauer, Andre A1 - Krenkel, Lars A1 - Birkenmaier, Clemens A1 - Lehle, Karla T1 - Accumulations of von Willebrand factor within ECMO oxygenators: Potential indicator of coagulation abnormalities in critically ill patients? JF - Artificial Organs N2 - Clot formation within membrane oxygenators (MOs) remains a critical problem during extracorporeal membrane oxygenation (ECMO). The composition of the clots-in particular, the presence of von Willebrand factor (vWF)-may be an indicator for prevalent nonphysiological flow conditions, foreign body reactions, or coagulation abnormalities in critically ill patients. Mats of interwoven gas exchange fibers from randomly collected MOs (PLS, Maquet, Rastatt, Germany) of 21 patients were stained with antibodies (anti-vWF and anti-P-selectin) and counterstained with 4 ',6-diamidino-2-phenylindole. The extent of vWF-loading was correlated with patient and technical data. While 12 MOs showed low vWF-loadings, 9 MOs showed high vWF-loading with highest accumulations close to crossing points of adjacent gas fibers. The presence and the extent of vWF-fibers/"cobwebs," leukocytes, platelet-leukocyte aggregates (PLAs), and P-selectin-positive platelet aggregates were independent of the extent of vWF-loading. However, the highly loaded MOs were obtained from patients with a significantly elevated SOFA score, severe thrombocytopenia, and persistent liver dysfunction. The coagulation abnormalities of these critically ill patients may cause an accumulation of the highly thrombogenic and elongated high-molecular-weight vWF multimers in the plasma which will be trapped in the MOs during the ECMO therapy. KW - ECMO KW - PLATELET ACTIVATION KW - THROMBOSIS KW - BLOOD FLOW KW - INFLAMMATION Y1 - 2019 U6 - https://doi.org/10.1111/aor.13513 SN - 1525-1594 VL - 43 IS - 11 SP - 1065 EP - 1076 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Philipp, Alois A1 - de Somer, Filip A1 - Foltan, Maik A1 - Bredthauer, Andre A1 - Krenkel, Lars A1 - Zeman, Florian A1 - Lehle, Karla T1 - Life span of different extracorporeal membrane systems for severe respiratory failure in the clinical practice JF - PLOS ONE N2 - Over the past decade, veno-venous extracorporeal membrane oxygenation (vvECMO) has been increasingly utilized in respiratory failure in patients. This study presents our institution´s experience focusing on the life span of ECMO systems reflecting the performance of a particular system. A retrospective review of our ECMO database identified 461 adult patients undergoing vvECMO (2010-2017). Patients that required more than one system and survived the first exchange >24 hours (n = 139) were included. Life span until the first exchange and exchange criteria were analyzed for all systems (PLS, Cardiohelp HLS-set, both Maquet Cardiopulmonary, Rastatt, Germany; Deltastream/Hilite7000LT, iLA-activve, Xenios/NovaLung, Heilbronn, Germany; ECC.O5, LivaNova, Mirandola, Italy). At our ECMO center, the frequency of a system exchange was 30%. The median (IQR) life span was 9 (6-12) days. There was no difference regarding the different systems (p = 0.145 and p = 0.108, respectively). However, the Deltastream systems were exchanged more frequently due to elective technical complications (e. g. worsened gas transfer, development of coagulation disorder, increased bleedings complications) compared to the other exchanged systems (p = 0.013). In summary, the used ECMO systems are safe and effective for acute respiratory failure. There is no evidence for the usage of a specific system. Only the increased predictability of an imminent exchange preferred the usage of a Deltastream system. However, the decision to use a particular system should not depend solely on the possible criteria for an exchange. KW - Equipment Failure Analysis/statistics & numerical data KW - Extracorporeal Membrane Oxygenation/instrumentation KW - Membrane/classification/standards/statistics & numerical data KW - Primary Health Care/statistics & numerical data KW - Respiratory Distress Syndrome/therapy KW - Retrospective Studies KW - Severity of Illness Index KW - Time factors KW - MULTIDETECTOR COMPUTED-TOMOGRAPHY KW - THROMBOTIC DEPOSITS KW - ECMO SYSTEMS KW - Flow KW - OXYGENATION Y1 - 2018 U6 - https://doi.org/10.1371/journal.pone.0198392 VL - 13 IS - 6 SP - 1 EP - 10 PB - PLOS ER - TY - CHAP A1 - Schaeffer, Leon A1 - Herrmann, David A1 - Böhm, Valter T1 - Theoretical considerations on a 2D compliant tensegrity joint in context of a biomedical application T2 - Engineering for a changing world : 60th ISC, Ilmenau Scientific Colloquium, Technische Universität Ilmenau, September 4-8, 2023 N2 - In this paper, a two-dimensional compliant tensegrity joint was investigated for potential biomedical applications such as orthotics or exoskeletons. The structure consists of two compressed members connected by five compliant tensioned members. The concept is based on the tensegrity principle, which allows the realization of dynamic orthoses without conventional hinge joints. Another advantage is the adaptability to the individual needs of the patient through a suitable design of the structure and the careful selection of the characteristics of the elements. Using geometric nonlinear analysis, the mechanical behavior of the structure was investigated, focusing on mechanical compliance. The main objective was to determine the influence of the initial length and stiffness of the tensioned members and the influence of the magnitude of external forces on the overall stiffness of the movable member of the structure. The results highlight the significant impact of member parameters on the structure's stiffness and movability under varying load magnitudes. The research laid the foundation for future development of dynamic orthoses based on this structure. Y1 - 2023 U6 - https://doi.org/10.22032/dbt.58879 SP - 1 EP - 15 PB - Technische Universität Ilmenau CY - Ilmenau ER - TY - CHAP A1 - Schaeffer, Leon A1 - Herrmann, David A1 - Böhm, Valter T1 - Voruntersuchung einer vorgespannten nachgiebigen Struktur für den Einsatz in dynamischen Handorthesen T2 - 9. IFToMM D-A-CH Konferenz, 16./17. März 2023, Universität Basel N2 - In diesem Beitrag erfolgt die theoretische Untersuchung einer zweidimensionalen nachgiebigen Tensegrity-Struktur in Hinsicht auf ihre potenzielle Eignung als Basisstruktur für eine dynamische Handorthese. Translatorische und rotatorische relative Bewegungsmöglichkeiten zwischen den Drucksegmenten der Struktur sind möglich, da diese Segmente durch nachgiebige Zugsegmente miteinander verbunden sind. Die Form der Struktur und ihre Vorspannung in einer statisch stabilen Gleichgewichtskonfiguration werden mit Hilfe der Minimierung des Kräfte- und Momentenungleichgewichts, der Betrachtung der potentiellen Energie der Struktur und einem Ansatz mittels statischer Finite-Elemente-Methode (FEM) in Abhängigkeit der Segmentparameter untersucht. N2 - This paper presents a theoretical investigation of a two-dimensional compliant tensegrity structure with respect to its potential suitability as a base structure for a dynamic hand orthosis. Translational and rotational relative motion possibilities between the pressure segments of the structure are possible, as these segments are connected by compliant tension segments. The shape of the structure and its preload in a static stable equilibrium configuration are investigated using minimization of force and moment imbalance, consideration of the potential energy of the structure, and a static finite element method (FEM) approach as a function of segment parameters. T2 - Preliminary investigation of a prestressed compliant structure for use in dynamic hand orthoses Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:465-20230314-153711-8 PB - DuEPublico CY - Duisburg-Essen ER - TY - CHAP A1 - Schaeffer, Leon A1 - Herrmann, David A1 - Böhm, Valter T1 - Preliminary considerations on the form-finding of a tensegrity joint to be used in dynamic orthoses T2 - 8th International Conference on Biomedical Engineering and Applications (ICBEA 2024), Tokio, 18-21. March 2024 Y1 - 2024 PB - ACM ET - accepted paper ER - TY - JOUR A1 - Bartsch, Alexander A1 - Beham, Daniela A1 - Gebhardt, Jakob A1 - Ehrlich, Ingo A1 - Schratzenstaller, Thomas A1 - Monkman, Gareth J. T1 - Mechanical Properties of NdPrFeB Based Magnetoactive Bisphenol-Free Boron-Silicate Polymers JF - Journal of Nanomedicine and Nanotechnology N2 - Following a ban on many materials containing bisphenol-A, new bisphenol-free Boron silicates have been found as substitutes. The purpose of this study is to describe the mechanical properties of these bisphenol-free magnetoactive borosilicate polymers containing hard magnetic particles. Samples of 0%, 33% and 66% by wt. were loaded for compression using a universal testing machine. The maximum forces occurring for different travel speeds were compared before and after post-magnetization treatments. The post-magnetization included 2 stages. In addition, the change in mechanical properties within 24 hours after the post-magnetization process was investigated. Furthermore, the influence of speed and particle content were investigated. In general, there is a correlation between the required compressive force and, the level of post-magnetization stress, the increase in travel speed and particle content in the boron silicate. Comparison of the non-post-magnetized and post-magnetized samples using two-tailed t-tests shows that the p-values for all weight fraction changes in NdPrFeB particles and travel speeds are less than 0.001. Also, a comparison between tests in which the traverse speed was varied also showed significant changes in the resulting compression forces. The same is valid for changes in the weight ratio of the NdPrFeB particles in the samples. For post-magnetized samples, no significant difference can be observed in the first 24 hours following magnetization. In summary, the material presents viscoelastic, plastic force-displacement behavior, which can be well recognized by its bi-linear curve shape. The investigation shows that borosilicate polymers based on NdPrFeB can have their mechanical behavior modified and controlled by post-magnetization processes. This opens new possibilities for many future applications. Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-67425 UR - https://www.walshmedicalmedia.com/open-access/mechanical-properties-of-ndprfeb-based-magnetoactive-bisphenolfree-boronsilicate-polymers-124385.html SN - 2157-7439 N1 - Corresponding author: Alexander Bartsch VL - 14 IS - 6 PB - Walsh Medical Media ER - TY - JOUR A1 - Haus, Moritz A1 - Foltan, Maik A1 - Philipp, Alois A1 - Mueller, Thomas A1 - Lingel, Maximilian P. A1 - Krenkel, Lars A1 - Gruber, Michael A1 - Lehle, Karla T1 - Neutrophil extracellular traps -a potential trigger for the development of thrombocytopenia during extracorporeal membrane oxygenation N2 - Neutrophil extracellular traps (NETs) have recently emerged as a potential link between inflammation, immunity, and thrombosis, as well as other coagulation disorders which present a major challenge in the context of extracorporeal membrane oxygenation (ECMO). By examining blood from ECMO patients for NETs and their precursors and correlating them with clinical and laboratory biomarkers of coagulation and inflammation, this study aims to evaluate the association between the presence of NETs in the bloodstream of ECMO patients and the development of potentially severe coagulation disorders during ECMO therapy. Therefore, blood samples were collected from healthy volunteers (n=13) and patients receiving veno-venous (VV) ECMO therapy (n=10). To identify NETs and their precursors, DNA and myeloperoxidase as well as granulocyte marker CD66b were visualized simultaneously by immunofluorescence staining in serial blood smears. Differentiation of DNA-containing objects and identification of NETs and their precursors was performed semiautomatically by a specific algorithm using the shape and size of DNA staining and the intensity of MPO and CD66b signal. Neutrophil extracellular traps and their precursors could be detected in blood smears from patients requiring VV ECMO. Compared to volunteers, ECMO patients presented significantly higher rates of NETs and NET precursors as well as an increased proportion of neutrophil granulocytes in all detected nucleated cells. A high NET rate prior to the initiation of ECMO therapy was associated with both increased iL-6 and TNF-α levels as an expression of a high cytokine burden. These patients with increased NET release also presented an earlier and significantly more pronounced decrease in platelet counts and ATIII activity following initiation of therapy compared with patients with less elevated NETs. These findings provide further indications for the development of immune-mediated acquired thrombocytopenia in ECMO patients. KW - Neutrophil extracellular traps (NET) KW - Immunoflorescence KW - Thrombocytopenia KW - Extracorporeal membrane oxygenation (ECMO) KW - Sepsis KW - immunothrombosis KW - Coagulation disorder Y1 - 2024 UR - https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2024.1339235/abstract U6 - https://doi.org/10.3389/fimmu.2024.1339235 VL - 15 PB - frontiers ER - TY - JOUR A1 - Lichtenauer, Norbert A1 - Ettl, Katrin A1 - Mohr, Christa A1 - Weber, Karsten A1 - Meussling-Sentpali, Annette T1 - Der Pflegeroboter für zu Hause JF - Die Schwester, der Pfleger N2 - Ein interdisziplinäres Forschungsprojekt der Ostbayerischen Hochschule Regensburg untersucht, inwiefern Telemedizin und digitale Anwendungen die Therapie und Pflege von Menschen mit Schlaganfall in ihrem häuslichen Umfeld unterstützen, ihre Lebensqualität beeinflussen und die intersektorale Versorgung verbessern kann. Y1 - 2021 UR - https://www.bibliomed-pflege.de/sp/artikel/44176-der-pflegeroboter-fuer-zu-hause VL - 11 IS - 21 SP - 48 EP - 52 PB - Bibliomed-Medizinische Verlagsgesellschaft mbH ER - TY - JOUR A1 - Wagner, Maria Stella A1 - Kranz, Michael A1 - Krenkel, Lars A1 - Pointner, Daniel A1 - Foltan, Maik A1 - Lubnow, Matthias A1 - Lehle, Karla ED - Becatti, Matteo T1 - Computer based visualization of clot structures in extracorporeal membrane oxygenation and histological clot investigations for understanding thrombosis in membrane lungs JF - Frontiers in Medicine N2 - Extracorporeal membrane oxygenation (ECMO) was established as a treatment for severe cardiac or respiratory disease. Intra-device clot formation is a common risk. This is based on complex coagulation phenomena which are not yet sufficiently understood. The objective was the development and validation of a methodology to capture the key properties of clots deposed in membrane lungs (MLs), such as clot size, distribution, burden, and composition. One end-oftherapy PLS ML was examined. Clot detection was performed using multidetector computed tomography (MDCT), microcomputed tomography (μCT), and photography of fiber mats (fiber mat imaging, FMI). Histological staining was conducted for von Willebrand factor (vWF), platelets (CD42b, CD62P), fibrin, and nucleated cells (4′, 6-diamidino-2-phenylindole, DAPI). The three imaging methods showed similar clot distribution inside the ML. Independent of the imaging method, clot loading was detected predominantly in the inlet chamber of the ML. The μCT had the highest accuracy. However, it was more expensive and time consuming than MDCT or FMI. The MDCT detected the clots with low scanning time. Due to its lower resolution, it only showed clotted areas but not the exact shape of clot structures. FMI represented the simplest variant, requiring little effort and resources. FMI allowed clot localization and calculation of clot volume. Histological evaluation indicated omnipresent immunological deposits throughout the ML. Visually clot-free areas were covered with leukocytes and platelets forming platelet-leukocyte aggregates (PLAs). Cells were embedded in vWF cobwebs, while vWF fibers were negligible. In conclusion, the presented methodology allowed adequate clot identification and histological classification of possible thrombosis markers such as PLAs. KW - ECMO KW - membrane lung KW - µCT KW - MDCT KW - shear induced clotting KW - vWF KW - histological evaluation Y1 - 2024 U6 - https://doi.org/10.3389/fmed.2024.1416319 IS - 11 PB - Frontiers ER - TY - INPR A1 - Förstl, Nikolas A1 - Adler, Ina A1 - Süß, Franz A1 - Dendorfer, Sebastian T1 - Technologies for Evaluation of Pelvic Floor Functionality: A Systematic Review N2 - Pelvic floor dysfunction is a common problem in women and has a negative impact ontheir quality of life. The aim of this review was to provide a general overview of the current state oftechnology used to assess pelvic floor functionality. It also provides literature research of the phys-iological and anatomical factors that correlate with pelvic floor health. The systematic review wasconducted according to the PRISMA guidelines. PubMed, ScienceDirect, Cochrane Library andIEEE databases were searched for publications on sensor technology for the assessment of pelvicfloor functionality. Anatomical and physiological parameters were identified through a manualsearch. In the systematic review 115 publications were included. 12 different sensor technologieswere identified. Information on the obtained parameters, sensor position, test activities and subjectcharacteristics were prepared in tabular form from each publication. 16 anatomical and physiologi- cal parameters influencing pelvic floor health were identified in 17 published studies and rankedfor their statistical significance. Taken together, this review could serve as a basis for the develop-ment of novel sensors which could allow for quantifiable prevention and diagnosis, as well as par-ticularized documentation of rehabilitation processes related to pelvic floor dysfunctions. KW - pelvic floor KW - sensors KW - functionality KW - influence parameters Y1 - 2024 U6 - https://doi.org/10.31219/osf.io/dcqyg N1 - Der Aufsatz wurde peer-reviewd veröffentlich und ist ebenfalls in diesem Repositorium verzeichnet unter: https://opus4.kobv.de/opus4-oth-regensburg/frontdoor/index/index/docId/7321 PB - Center for Open Science ER - TY - JOUR A1 - Auer, Simon A1 - Süß, Franz A1 - Dendorfer, Sebastian T1 - Using markerless motion capture and musculoskeletal models: An evaluation of joint kinematics JF - Technology and Health Care N2 - BACKGROUND: This study presents a comprehensive comparison between a marker-based motion capture system (MMC) and a video-based motion capture system (VMC) in the context of kinematic analysis using musculoskeletal models. OBJECTIVE: Focusing on joint angles, the study aimed to evaluate the accuracy of VMC as a viable alternative for biomechanical research. METHODS: Eighteen healthy subjects performed isolated movements with 17 joint degrees of freedom, and their kinematic data were collected using both an MMC and a VMC setup. The kinematic data were entered into the AnyBody Modelling System, which enables the calculation of joint angles. The mean absolute error (MAE) was calculated to quantify the deviations between the two systems. RESULTS: The results showed good agreement between VMC and MMC at several joint angles. In particular, the shoulder, hip and knee joints showed small deviations in kinematics with MAE values of 4.8∘, 6.8∘ and 3.5∘, respectively. However, the study revealed problems in tracking hand and elbow movements, resulting in higher MAE values of 13.7∘ and 27.7∘. Deviations were also higher for head and thoracic movements. CONCLUSION: Overall, VMC showed promising results for lower body and shoulder kinematics. However, the tracking of the wrist and pelvis still needs to be refined. The research results provide a basis for further investigations that promote the fusion of VMC and musculoskeletal models. KW - biomechanics KW - range of motion KW - musculoskeletal system KW - optical motion capture Y1 - 2024 U6 - https://doi.org/10.3233/THC-240202 SN - 0928-7329 N1 - Corresponding author der OTH Regensburg: Sebastian Dendorfer SP - 1 EP - 10 PB - IOS Press ER - TY - JOUR A1 - Förstl, Nikolas A1 - Adler, Ina A1 - Süß, Franz A1 - Dendorfer, Sebastian T1 - Technologies for Evaluation of Pelvic Floor Functionality: A Systematic Review JF - Sensors N2 - Pelvic floor dysfunction is a common problem in women and has a negative impact on their quality of life. The aim of this review was to provide a general overview of the current state of technology used to assess pelvic floor functionality. It also provides literature research of the physiological and anatomical factors that correlate with pelvic floor health. This systematic review was conducted according to the PRISMA guidelines. The PubMed, ScienceDirect, Cochrane Library, and IEEE databases were searched for publications on sensor technology for the assessment of pelvic floor functionality. Anatomical and physiological parameters were identified through a manual search. In the systematic review, 114 publications were included. Twelve different sensor technologies were identified. Information on the obtained parameters, sensor position, test activities, and subject characteristics was prepared in tabular form from each publication. A total of 16 anatomical and physiological parameters influencing pelvic floor health were identified in 17 published studies and ranked for their statistical significance. Taken together, this review could serve as a basis for the development of novel sensors which could allow for quantifiable prevention and diagnosis, as well as particularized documentation of rehabilitation processes related to pelvic floor dysfunctions. Y1 - 2024 U6 - https://doi.org/10.3390/s24124001 N1 - Die Preprint-Version ist ebenfalls in diesem Repositorium verzeichnet unter: https://opus4.kobv.de/opus4-oth-regensburg/frontdoor/index/index/docId/7306 VL - 24 IS - 12 PB - MDPI ER - TY - GEN A1 - Dendorfer, Sebastian T1 - Diagnostische Genauigkeit und klinische Anwendungen tragbarer Bewegungssensoren für die Kniegelenksrehabilitation Y1 - 2024 CY - Nürnberg ER - TY - JOUR A1 - Mühling, Mischa A1 - Sandriesser, Sabrina A1 - Dendorfer, Sebastian A1 - Augat, Peter T1 - Assessment of implant internal stresses under physiological femoral loading: Translation to a simplified bending load model JF - Journal of Biomechanics N2 - The success of surgical treatment for fractures hinges on various factors, notably accurate surgical indication. The process of developing and certifying a new osteosynthesis device is a lengthy and costly process that requires multiple cycles of review and validation. Current methods, however, often rely on predecessor standards rather than physiological loads in specific anatomical locations. This study aimed to determine actual loads experienced by an osteosynthesis plate, exemplified by a standard locking plate for the femoral shaft, utilizing finite elements analysis (FEA) and to obtain the bending moments for implant development standard tests. A protocol was developed, involving the creation and validation of a fractured femur model fixed with a locking plate, mechanical testing, and FEA. The model’s validation demonstrated exceptional accuracy in predicting deformations, and the FEA revealed peak stresses in the fracture bridging zone. Results of a parametric analysis indicate that larger fracture gaps significantly impact implant mechanical behavior, potentially compromising stability. This study underscores the critical need for realistic physiological conditions in implant evaluations, providing an innovative translational approach to identify internal loads and optimize implant designs. In conclusion, this research contributes to enhancing the understanding of implant performance under physiological conditions, promoting improved designs and evaluations in fracture treatments. KW - bone biomechanics KW - finite elements analysis KW - femoral fracture KW - Euler-Bernoulli-Beam-Theory KW - simplified loading model Y1 - 2024 U6 - https://doi.org/10.1016/j.jbiomech.2024.112229 SN - 1873-2380 IS - 112229 PB - Elsevier ER - TY - JOUR A1 - Zentgraf, Jan A1 - Nützel, Florian A1 - Mühlbauer, Nico A1 - Schultheiss, Ulrich A1 - Grad, Marius A1 - Schratzenstaller, Thomas T1 - Surface Treatment of Additively Manufactured Polyetheretherketone (PEEK) by Centrifugal Disc Finishing Process: Identification of the Key Parameters JF - Polymers N2 - Polyetheretherketone is a promising material for implants due to its good mechanical prop- erties and excellent biocompatibility. Its accessibility to a wide range of applications is facilitated by the ability to process it with an easy-to-use manufacturing process such as fused filament fabrication. The elimination of disadvantages associated with the manufacturing process, such as a poor surface quality, is a main challenge to deal with. As part of the mass finishing process, centrifugal disc finishing has demonstrated good results in surface optimization, making it a promising candidate for the post-processing of additively manufactured parts. The objective of this study is to identify the key parameters of the centrifugal disc finishing process on the waviness of additively manufactured PEEK specimens, which has not been investigated previously. The waviness of the specimen was investigated by means of confocal laser scanning microscopy (CLSM), while weight loss was additionally tracked. Six parameters were investigated: type, amount and speed of media, use of compound, amount of water and time. Type of media, time and speed were found to significantly influence waviness reduction and weight loss. Surface electron microscopy images demonstrated the additional effects of deburring and corner rounding. Results on previous studies with specimens made of metal showed similar results. Further investigation is required to optimize waviness reduction and polish parts in a second post-processing step. KW - PEEK KW - fused deposition modeling KW - fused filament fabrication KW - centrifugal disc finishing KW - mass finishing KW - 3D printing KW - post-processing of 3D printed parts KW - surface treatment KW - high-performance polymers KW - additive manufacturing Y1 - 2024 U6 - https://doi.org/10.3390/polym16162348 SN - 2073-4360 VL - 16 PB - MDPI CY - Basel ER - TY - GEN ED - Frommeld, Debora ED - Scorna, Ulrike ED - Haug, Sonja ED - Weber, Karsten T1 - Gute Technik für ein gutes Leben im Alter? BT - Akzeptanz, Chancen und Herausforderungen altersgerechter Assistenzsysteme N2 - Längst gibt es altersgerechte digitale Assistenzsysteme. Doch sind Umfang und Geschwindigkeit ihrer Verbreitung sowohl in Pflegeeinrichtungen als auch in privaten Haushalten weitgehend unbekannt. Informationen zu tatsächlich eingesetzten Systemen, realisierten Umsätzen und Marktvolumen sind kaum zu finden. Obwohl es viele Vermutungen hinsichtlich der Hindernisse bei der Einführung altersgerechter Assistenzsysteme gibt, sind auch hier verlässliche Aussagen rar. Die Beiträge des Bandes liefern auf Basis empirischer Untersuchungen und theoretischer Überlegungen Antworten und zeigen auf, wie vielgestaltig die Faktoren sind, die die Diffusion altersgerechter Assistenzsysteme hemmen oder fördern. KW - Alter KW - Altenpflege KW - Assistenzsystem KW - Künstliche Intelligenz KW - Medizintechnik KW - Arbeitshilfe Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-149 SN - 978-3-8376-5469-1 PB - transcript Verlag CY - Bielefeld ER -