OPUS THD (Technischen Hochschule Deggendorf)
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A Reflection on Current Definitions of Critical Care and Critical Illness—A Narrative Review of the Literature
No full textBackground
Critical care and critical illness are key concepts that have been defined in various publications. A common understanding of the concepts is of great importance, but an up‐to‐date overview and discussion are lacking in the literature.
Aim
The aim of this study was to identify and discuss current definitions of critical care, critical illness and chronic critical illness.
Study Design
We conducted a narrative review and performed literature searches in Medline, Cochrane Library, CINAHL, Embase, LIVIVO, Google Scholar, OpenGrey, Epistemonikos and Science Open as well as citation searching from July 2024 to September 2025. Reports on definitions were included if they dealt thematically with critical care, critical illness or chronic critical illness, were published within the last 10 years and were available in German or English. Data synthesis followed an inductive approach. We thematically analysed the core concepts of identified definitions, formed thematic clusters and finally approved them in multiple group discussions.
Results
In total, 13 definitions of critical care, eight definitions of critical illness and 12 definitions of chronic critical illness were identified. Key components of critical care are the population, interventions, timing, professionals, aim, location and complexity. Critical illness is mainly characterised by future aspects and prevention, underlying causes and treatment. Chronic critical illness is determined by its duration, several complications and frailty. All three terms share the temporality and severity of a disease. Included definitions have a pronounced pathophysiological focus; they point to highly complex and technologised treatment pathways.
Conclusion
Current definitions show a generally homogeneous understanding of the care for critically ill patients. To ensure a comprehensive representation, definitions need to be adapted and consider the experiences of those involved.
Relevance to Clinical Practice
The analysed clusters of the definitions of critical care, critical illness and chronic critical illness help professionals to develop their terminology and reflect on their clinical approaches
Are Ecosystem Services Replaceable by Technology Yet? Bio-Inspired Technologies for Ecosystem Services: Challenges and Opportunities
No full textAs ecological collapse accelerates under the pressures of anthropogenic climate change, adaptation strategies increasingly include technological proxies for nature’s functions. But can ecosystem services (ES) be meaningfully replaced by technology? Revisiting this urgent question first posed by Fitter (2013), we assess the extent to which bio-inspired design—particularly biomimetics—has advanced the capacity to support, enhance, or replace natural ES. We convened an interdisciplinary team to synthesize and refine a comprehensive list of 22 ecosystem services, integrating often-overlooked cultural and relational dimensions. Using this framework, we conducted a large-scale analysis of over 68,000 peer-reviewed publications from the biomimetics and bio-inspired design literature between 2004 and 2025, applying AI-assisted classification to evaluate whether, and how, these technologies map onto specific ES functions and benefits. Our findings reveal both promise and profound limitations. Bio-inspired research engages with 20 of the 22 ES, but over 78% of this work concentrates on five technologically tractable functions—biochemicals, disease regulation, waste treatment, fibre/hide/wood, and fuel. Foundational supporting and regulating services such as pollination, soil formation, and nutrient cycling are almost entirely absent. Moreover, only 3% of technologies described in the academic literature aim to support existing systems; the overwhelming emphasis on enhancement (39%) and replacement (58%) suggests a design paradigm skewed toward substitution rather than coexistence. Intangible, co-produced services—particularly those related to culture, identity, and meaning—remain outside the current reach of biomimetic design. This skew reveals a dangerous imbalance: while certain ES can be technologically approximated, the relational, emergent, and systemic qualities of ecosystems elude replication. Technological replacement must not become a substitute for preservation. Instead, bio-inspired design should be mobilized as a tool for adaptation that amplifies and protects the living systems on which human and more-than-human futures depend
Framework for Processing of CRISM Hyperspectral Data for Global Martian Mineralogy
No full textHighlights
What are the main findings?
• Processing CRISM hyperspectral data remains challenging due to high dimensionality and striping noise; this study presents a framework for global mineralogical mapping by implementing filtering and algorithmic optimization to improve the generation of spectral cluster maps (SCMs).
• The adaptation and automation of previously manual procedures, such as determining the optimal number of clusters, enable the efficient and reproducible production of global mineralogical maps.
What are the implications of the main findings?
• The robust clustering process now allows the large-scale generation of mineralogical maps in the form of SCMs from CRISM data.
• The proposed framework builds the basis for an automated processing pipeline, enabling a scalable, global mineralogical analysis of the Martian surface without the need for manual intervention.
Abstract
Hyperspectral data from CRISM have proven invaluable for analyzing the mineralogical composition of the Martian surface. However, processing such datasets remains challenging due to their high dimensionality and systematic noise, such as striping artifacts caused by the pushbroom imaging technique. Building on previous research, this study introduces a framework that forms the basis for an automated pipeline that combines preprocessing, dimensionality reduction using UMAP, k-means clustering, and an adaptive stripe correction filter to generate mineral maps of the Martian surface. Additionally, the pipeline integrates a noise variance estimation step based on PCA to assess the feasibility and expected efficacy of stripe removal before applying the filter. We validate the methodology across multiple CRISM datasets, including regions such as Jezero Crater, Nili Fossae, and Mawrth Vallis. Comparative analyses using metrics such as the CH index, DB index, and SC demonstrate improved clustering performance and robust mineralogical mapping, which indicates a step toward more reliable and automated clustering of CRISM data. Furthermore, the pipeline leverages spectral libraries for automated mineral classification, yielding results comparable to expert-defined maps while addressing discrepancies caused by residual noise or clustering limitations. This study represents a step toward fully automated, scalable geospatial analysis of CRISM Martian surface data, offering a robust framework for processing large hyperspectral datasets and supporting future planetary exploration missions. In the future, we intend to deploy an automated analysis pipeline as a freely accessible web service
Acidic melanoma microenvironment selects for a senescence-like but also migratory-active subpopulation driving metastatic disease
No full textAbstract
One of the main characteristics of solid tumors, such as melanoma, is an acidic tumor microenvironment. Due to dysregulation of the cancer cell metabolism and an increased production of acidic metabolites, the tumor acidifies its microenvironment. We hypothesize that this has a strong impact on tumor heterogeneity and the formation of phenotypic subpopulations. Cell culture experiments are usually carried out at a physiological pH of 7.4. Here, we show that long-time acidosis results in the formation of a senescent subpopulation in melanoma cells. Interestingly, after reintroduction to physiological pH, these cells lose their senescence-associated attributes. We isolated this subpopulation using β-galactosidase-dependent C12FDG staining and FACS. Live cell imaging, microscopy, and RNA sequencing analysis revealed that these apparent senescent cells show an increased migratory activity. With this study, we demonstrate that the acidic tumor microenvironment drives tumor plasticity in melanoma and results in the formation of a small subpopulation, which promotes metastasis
Comparison of safety and efficacy in venous access closure using a double purse string suture technique vs. Z-suture technique after MitraClip procedure
No full textBackground
Percutaneous mitral valve repair using the MitraClip System is a well-established therapeutic option for patients with symptomatic mitral regurgitation. This procedure is usually performed via venous femoral access using a 24-French guiding catheter. Since vascular complications and bleeding remain a relevant limitation, we now compared access closure using subcutaneous absorbable double purse string suture (DPSS) and Z-suture technique following MitraClip procedure.
Methods
249 patients (mean age 76 ± 8 years) who underwent MitraClip procedure at our institution were included. Venous closure was performed using Z-suture technique in 140 patients and DPSS technique in 109 patients. Vascular complications and bleeding events were assessed according to the Mitral Valve Academic Research Consortium (MVARC) criteria.
Results
MVARC minor and major vascular complications were comparable after closure with Z-suture and DPSS-technique (4.3% vs. 0.9%, p = 0.11 and 1.4% vs. 0.9%, p = 0.71, respectively). However, development of AV-fistula and requirement of access related surgical intervention was more often observed in the Z-suture group (5% vs. 0%, p = 0.018 and 3.5% vs. 0%, p = 0.045). MVARC minor and major, non-life-threatening bleeding did not differ between the two groups (10.7% vs. 12.9%, p = 0.61 and 0.7% vs. 0.0%, p = 0.38). Similarly, overall transfusion rates and access related blood transfusion rates were comparable (11.4% vs. 15.5%, p = 0.34 and 4.3% vs. 2.7%, p = 0.52).
Conclusion
Large caliber venous access closure with DPSS technique was feasible, safe, and effective to achieve haemostasis after MitraClip procedure. Compared with Z-suture, use of DPSS closure was associated with a lower rate of required access related surgical intervention and postinterventional AV-fistula
Ramadanov–Zabler Safe Zone for Sacroiliac Screw Placement: A CT-Based Computational Pilot Study
No full textBackground/Objectives
Posterior pelvic ring fractures are severe injuries requiring surgical stabilization, often through sacroiliac (SI) screw fixation. However, improper screw placement poses risks of neurovascular injury and implant failure. Defining a precise safe zone for screw placement is crucial to improving surgical accuracy and reducing complications.
Methods
A computational study was conducted using a CT scan of a 75-year-old male patient to establish a safe zone for SI screw placement. Manual segmentation and 3D modeling techniques were used to analyze bone density distribution. A 2D lateral projection of the sacrum was generated to identify high-density regions optimal for screw placement. While the general principle of targeting areas of higher bone density for screw insertion is well established, this study introduces a novel computational method to define and visualize such a safe zone. The resulting region, termed the Ramadanov–Zabler Safe Zone, was delineated based on this analysis to ensure maximal intraosseous fixation with minimal risk of cortical breaches.
Results
A high-resolution 3D model of the sacral region was successfully generated. Standard thresholding methods for segmentation proved ineffective due to low bone density, necessitating a freehand approach. The derived 2D projection revealed regions of higher bone density, which were defined as the Ramadanov-Zabler Safe Zone for screw insertion. This zone correlates with areas providing the best structural integrity, thereby reducing risks associated with screw misplacement. Additionally, intraoperative and postoperative imaging from a representative case is included to illustrate the translational feasibility of the proposed technique.
Conclusions
The Ramadanov–Zabler Safe Zone offers a reproducible, CT-based computational approach to guide for SI screw placement, enhancing surgical precision and patient safety. This CT-based computational approach provides a standardized reference for preoperative planning, minimizing neurovascular complications and improving surgical outcomes. This pilot technique is supported by preliminary clinical imaging that demonstrates feasibility for intraoperative application. Further validation across diverse patient populations is recommended to confirm its clinical applicability
Do Meta‐Analyses of Total Hip Arthroplasty Produce Reliable Results? A Systematic Review and Meta‐Epidemiological Study of Statistical Methods
No full textBackground
Total hip arthroplasty (THA) is a highly successful orthopedic procedure, with numerous meta‐analyses published to optimize its outcomes. However, the reliability of their results and conclusions depends heavily on the use of appropriate statistical methods. Therefore, the aim was to test the reliability of statistical methods in meta‐analyses of THA by examining the degree of heterogeneity, the effect of different between‐study variance estimators, and the equality of sample size of pooled primary studies.
Methods
The literature was systematically searched in PubMed from January 1, 2022, to December 31, 2023, for meta‐analyses on THA. The quality of the meta‐analyses was assessed using the revised Measurement Tool to Assess Systematic Reviews (AMSTAR 2). All meta‐analyses were recalculated using eight different heterogeneity estimators. The following indicators were considered: inequality of patient numbers, proportion of random‐effects and fixed‐effects models, heterogeneity with I
2 value, ratio of effect sizes (RES), ratio of confidence interval width (RCIW), and the number of significant results. Mixed linear regression was then used to analyze whether the effect sizes and CIW were significantly different using different heterogeneity estimators. Finally, all examined meta‐analyses were recalculated using the eight heterogeneity estimators and the Hartung–Knapp (HK) adjustment.
Results
Of the 24 meta‐analyses examined, 15 reported an outcome using a mean difference and 20 reported an outcome using an odds ratio. The quality assessment identified 10 meta‐analyses of high quality, 7 of moderate quality, 4 of low quality, and 3 of critically low quality. The significance of the examined meta‐analyses varied considerably depending on the heterogeneity estimators used. In particular, the DerSimonian and Laird and Hunter–Schmidt heterogeneity estimators tended to produce false‐positive results. The meta‐analyses examined generally did not use HK adjustment. This effect is amplified when combined with the weak DerSimonian and Laird heterogeneity estimator, which were used in almost all examined meta‐analyses.
Conclusion
Without HK adjustment, the results depend strongly on the heterogeneity estimator chosen and there is a risk of false positives, especially for the widely used DerSimonian and Laird heterogeneity estimator. For HK adjustment, the choice of heterogeneity estimator seems to play a less important role. We recommend the use of more reliable heterogeneity estimators as well as the HK adjustment as a measure to improve the statistical methodology of meta‐analyses. This study highlights the critical need for improved statistical rigor in meta‐analyses of THA, ensuring more reliable evidence for clinical decision‐making and guideline development
Acceptability and feasibility of a group intervention for long COVID in Johannesburg, South Africa: a mixed-method study
No full textBackground
COVID-19 affected 777 million people globally, with 7.1 million deaths. In Africa, 9.6 million cases and 176,000 deaths were reported. Long COVID, a significant consequence of the COVID-19, presented by chronic symptoms, affects the physical and mental health, thereby impacting the quality of life. While high-income countries implemented rehabilitation programs for managing long COVID symptoms, low- and middle-income countries faced healthcare disparities. In South Africa, limited multidisciplinary interventions were evident. This study aimed to assess the acceptability and feasibility of an 8-week rehabilitation and self-management program for long COVID using mixed-methods approach in Johannesburg.
Methods
Patients and hospital staff who suffered from at least one symptom of long COVID for a period of two months and who consented to participate in the intervention were recruited from Tembisa Provincial Tertiary Hospital. The recruitment was from July to October 2023. Questionnaires were administered and interviews with selected participants were conducted to assess the acceptability and feasibility of the intervention. A descriptive analysis was carried out for the quantitative data, and a deductive thematic analysis was used for the interviews.
Results
The participants had positive perceptions towards the design of the intervention, delivery, materials used and support by research staff and external consultants such as dietitians, physiotherapists, and psychologists. The participants stated that the intervention had improved their knowledge of long COVID and increased their self-confidence. Major barriers related to the intervention perceived by the participants were infrastructure, time and language. Recommendations from the participants included expanding the intervention at the community level and extending the duration of the intervention beyond 8-weeks.
Conclusion
This pilot intervention, that aimed to manage the symptoms of long COVID, was well accepted by the participants and achieved its intended outcome. Similar interventions are required at the clinical as well as community levels
Generative Artificial Intelligence for Synthetic Spectral Data Augmentation in Sensor-Based Plastic Recycling
No full textThe reliance on deep learning models for sensor-based material classification amplifies the demand for labeled training data. However, acquiring large-scale, annotated spectral data for applications such as near-infrared (NIR) reflectance spectroscopy in plastic sorting remains a significant challenge due to high acquisition costs and environmental variability. This paper investigates the potential of large language models (LLMs) in synthetic spectral data generation. Specifically, it examines whether LLMs have acquired sufficient implicit knowledge to assist in generating spectral data and introduce meaningful variations that enhance model performance when used for data augmentation. Classification accuracy is reported exclusively as a proxy for structural plausibility of the augmented spectra; maximizing augmentation performance itself is not the study’s goal. From as little as one empirical mean spectrum per class, LLM-guided simulation produced data that enabled up to 86% accuracy, evidence that the generated variation preserves class-distinguishing information. While the approach performs best for spectral distinct polymers, overlapping classes remain challenging. Additionally, the transfer of optimized augmentation parameters to unseen classes indicates potential for generalization across material types. While plastic sorting serves as a case study, the methodology may be applicable to other domains such as agriculture or food quality assessment, where spectral data are limited. The study outlines a novel path toward scalable, AI-supported data augmentation in spectroscopy-based classification systems
Mean distraction force applied in tension‐controlled ligament‐balanced total knee arthroplasty: A systematic review and meta‐analysis
No full textPurpose
Proper tension of the collateral ligaments is the key to success in total knee arthroplasty (TKA). The study aimed to identify the distraction force for the medial and lateral femorotibial compartments in tension‐controlled ligament‐balanced TKA at 0° and 90° of knee flexion.
Methods
A literature search was conducted in PubMed up to 31 December 2024 to identify studies that reported exact values of the distraction force applied in tension‐controlled ligament‐balanced TKA. Mean distraction force at 0° and 90° of knee flexion were calculated for the native knee, cadaver knee, and computer model/artificial knee groups. Differences between groups were calculated using Kruskal–Wallis and Mann–Whitney U tests, with p ≤ 0.05 considered significant. A frequentist meta‐analysis of subgroup analysis between native and cadaver knee studies was performed using a random effects model with inverse variance and the Sidik–Jonkman heterogeneity estimator with Hartung–Knapp adjustment to calculate participant age and sex.
Results
Out of 116 included primary studies involved, a total of 6869 participants had distraction force measurements during TKA. The mean distraction force was 149.9 N (35.0–320.0 N) at 0° knee extension and 139.5 N (14.7–244.7 N) at 90° of flexion. Using the Kruskal–Wallis test or the Mann–Whitney U test, there were no significant differences in distraction force between native knee, cadaver knee, computer model/artificial knee studies at extension (p = 0.2480 and p = 0.1130) and at 90° of knee flexion (p = 0.8439 and p = 0.6241).
Conclusion
This meta‐analysis is the first to quantify distraction force in TKA, providing essential reference values of 149.9 N at 0° extension and 139.5 N at 90° flexion. These findings offer valuable guidelines for intraoperative soft tissue management during TKA procedures. The consistency of distraction force across different experimental models suggests that these values are broadly applicable. However, it remains unclear whether a more personalized distraction force should be considered for gap preparation.
Level of Evidence
Level IV