29 research outputs found
Using machine learning techniques for exploration and classification of laboratory data
No full textThe study aims to acquaint readers with six widely used machine learning (ML) techniques (Principal Component Analysis (PCA), Uniform Manifold Approximation and Projection (UMAP), k-means, hierarchical clustering and the decision tree models (rpart and random forest)) that might be useful for the analysis of laboratory data
Endoscopic Approach to the Quadrilateral Plate (EAQUAL): a New Endoscopic Approach for Plate Osteosynthesis of the Pelvic Ring and Acetabulum – a Cadaver Study
No full textZusammenfassung
Hintergrund Dislozierte Frakturen des Beckens werden üblicherweise über offene chirurgische Zugänge osteosynthetisch versorgt. Die zugangsbedingte Morbidität beträgt dabei nach Literaturangaben bis zu 30%. Ziel dieser anatomischen Studie war die Machbarkeit einer endoskopischen Visualisierung der in der Beckenchirurgie wichtigen anatomischen Strukturen sowie die Durchführung einer komplett endoskopischen Plattenosteosynthese des Azetabulums mit vorhandenem laparoskopischen Standardinstrumentarium.
Methodik An 4 anatomischen Ganzkörperpräparaten erfolgte die endoskopische Präparation des gesamten Beckenringes von der Symphyse bis zum Iliosakralgelenk. Dabei konnte die gesamte quadrilaterale Fläche bis hin zur Spina ischiadica mit dem N. ischiadicus dargestellt werden. Anschließend erfolgte eine komplett endoskopische Plattenosteosynthese entlang der Linea iliopectinea.
Ergebnisse Die endoskopische Präparation des Beckenringes und der quadrilateralen Fläche wird Schritt für Schritt dargestellt, gefolgt von einer komplett endoskopischen Osteosynthese entlang der Linea iliopectinea. Endoskopische, radiografische sowie schematische Darstellungen illustrieren die Technik.
Schlussfolgerung Die komplett endoskopische Präparation des Beckenringes und der quadrilateralen Fläche inkl. Plattenosteosynthese ist mit dem vorhandenen Standardinstrumentarium möglich. Bevor eine Implementierung in die klinische Versorgung erfolgen kann, müssen allerdings insbesondere Fragen zu Repositionsmöglichkeiten weiter untersucht werden.</jats:p
reflimLOD: A Modified reflimR Approach for Estimating Reference Limits with Tolerance for Values Below the Lower Limit of Detection (LOD)
No full textReference intervals are indispensable for the interpretation of medical laboratory results to distinguish “normal” from “pathological” values. Recently, indirect methods have been published, which estimate reference intervals from a mixture of normal and pathological values based on certain statistical assumptions on the distribution of the values from the healthy population. Some analytes face the problem that a significant proportion of the measurements are below the limit of detection (LOD), meaning that there are no quantitative data for these values, only the information that they are smaller than the LOD. Standard statistical methods for reference interval estimation are not designed to incorporate values below the LOD. We propose two variants of the indirect method reflimR—a quantile- and maximum likelihood-based estimator—that are able to cope with values below the LOD. We show, based on theoretical analyses, simulation experiments, and real data, that our approach yields good estimates for the reference interval, even when the values below the LOD contribute a substantial proportion to the data
How Gaussian mixture modelling can help to verify reference intervals from laboratory data with a high proportion of pathological values
No full textAlthough there are several indirect methods that can be used to verify reference limits, they have a common weakness in that they assume a low proportion of pathological values. This paper investigates whether a Gaussian decomposition algorithm can identify the non-pathological fraction even if it is not the main subset of mixed data
A Novel Tool for the Rapid and Transparent Verification of Reference Intervals in Clinical Laboratories
No full textBackground/Objectives: We present a software package called reflimR (Version 1.0.6), which enables rapid and transparent verification of reference intervals from routine laboratory measurements. Our method makes it easy to compare the results with specified target values and facilitates the interpretation of deviations using traffic light colors. Methods: The algorithm includes three procedural steps: (a) definition of an appropriate distribution model, based on Bowley’s quartile skewness, (b) iterative truncation, based on a modified boxplot method to obtain the central 95% of presumably inconspicuous results, and (c) extrapolation of reference limits from a truncated normal quantile–quantile plot. Results: All algorithms have been combined into one consolidated library, which can be called in the R environment with a single command reflim (x). Using an example dataset included in the package, we demonstrate that our method can be applied to mixed data containing a substantial proportion of pathological values. It leads to similar results as the direct guideline approach as well as the more sophisticated indirect refineR software package. As compared to the latter, reflimR works much faster and needs smaller datasets for robust estimates. For the interpretation of the results, we present an intuitive color scheme based on tolerance ranges (permissible uncertainty of laboratory results). We show that a relatively high number of published reference limits require careful reevaluation. Conclusions: The reflimR package closes the gap between direct guideline methods and the more sophisticated indirect refineR method. We recommend reflimR for the rapid routine verification of large amounts of reference limits and refineR for a careful analysis of unclear or doubtful results from this check
Rotational Stability of Scaphoid Osteosyntheses: An In Vitro Comparison of Small Fragment Cannulated Screws to Novel Bone Screw Sets.
No full textBACKGROUND:The current standard of care for operative repair of scaphoid fractures involves reduction and internal fixation with a single headless compression screw. However, a compression screw in isolation does not necessarily control rotational stability at a fracture or nonunion site. The single screw provides rotational control through friction and bone interdigitation from compression at the fracture site. We hypothesize that osteosyntheses with novel bone screw sets (BSS) equipped with anti-rotational elements provide improved rotational stability. METHODS:Stability of osteosynthesis under increasing cyclic torsional loading was investigated on osteotomized cadaveric scaphoids. Two novel prototype BSS, oblique type (BSS-obl.) and longitudinal type (BSS-long.) were compared to three conventional screws: Acutrak2®mini, HCS®3.0 and Twinfix®. Biomechanical tests were performed on scaphoids from single donors in paired comparison and analyzed by balanced incomplete random block design. Loading was increased by 50 mNm increments with 1,000 cycles per torque level and repeated until a rotational clearance of 10°. Primary outcome measure was the number of cycles to 10° clearance, secondary outcome measure was the maximum rotational clearance for each torque level. FINDINGS:BSS-obl. performed significantly better than Acutrak2®mini and HCS® (p = 0.015, p<0.0001). BSS-long. performed significantly better than HCS® (p = 0.010). No significant difference in performance between BSS-obl. and BSS-long. (p = 0.361), between BSS obl. and Twinfix® (p = 0.50) and BSS long. and Twinfix® (p = 0.667) was detected. Within the torque range up to 200 mNm, four of 21 (19%) BSS-long. and four of 21 (19%) BSS-obl. preparations showed early failure. The same loading led to early failure in four (29%) Twinfix®, seven (50%) Acutrak2®mini and 10 (71%) HCS® of 14 screw samples, respectively. CONCLUSIONS:For both BSS and to a lesser extent for Twinfix® (as dual-component screw), higher rotational stabilities were identified in comparison to single component headless compression screws
EASY (endoscopic approach to the symphysis): a new minimally invasive approach for the plate osteosynthesis of the symphysis and the anterior pelvic ring—a cadaver study and first clinical results
No full textCell-Free DNA in Plasma and Serum Indicates Disease Severity and Prognosis in Blunt Trauma Patients
No full textBackground: Trauma is still a major cause of mortality in people < 50 years of age. Biomarkers are needed to estimate the severity of the condition and the patient outcome. Methods: Cell-free DNA (cfDNA) and further laboratory markers were determined in plasma and serum of 164 patients at time of admission to the emergency room. Among them were 64 patients with severe trauma (Injury Severity Score (ISS) ≥ 16), 51 patients with moderate trauma (ISS < 16) and 49 patients with single fractures (24 femur neck and 25 ankle fractures). Disease severity was objectified by ISS and Glasgow Coma Scale (GCS). Results: cfDNA levels in plasma and serum were significantly higher in patients with severe multiple trauma (SMT) than in those with moderate trauma (p = 0.002, p = 0.003, respectively) or with single fractures (each p < 0.001). CfDNA in plasma and serum correlated very strongly with each other (R = 0.91; p < 0.001). The AUC in ROC curves for identification of SMT patients was 0.76 and 0.74 for cfDNA in plasma and serum, respectively—this was further increased to 0.84 by the combination of cfDNA and hemoglobin. Within the group of multiple trauma patients, cfDNA levels were significantly higher in more severely injured patients and patients with severe traumatic brain injury (GCS ≤ 8 versus GCS > 8). Thirteen (20.3%) of the multiple trauma patients died during the first week after trauma. Levels of cfDNA were significantly higher in non-surviving patients than in survivors (p < 0.001), reaching an AUC of 0.81 for cfDNA in both, plasma and serum, which was further increased by the combination with hemoglobin and leukocytes. Conclusions: cfDNA is valuable for estimation of trauma severity and prognosis of trauma patients
a-e. Screw types.
No full textThe shown screws were used for the test series: Acutrak®2mini (Acumed) (Fig 1a), Twinfix® (Stryker) (Fig 1b), HCS® 3.0 (Synthes) (Fig 1c), and prototypes of the two new BSS sets with an additional crosswise drill hole with an inner thread in oblique type (BSS-obl.) (Fig 1d) and with a longitudinal groove with an inner thread and longitudinal screw as a longitudinal type (BSS-long.) (Fig 1e).</p
a-d. Sample of a force/angle diagram.
No full textForce/angle diagrams of the cyclic load of a scaphoid bone with a torque load from 150 to 300 mNm and resulting loss of stability. In Fig 4d loosening of the screw fastening is clearly visible by the curves which run out to the right and the line up to 10°.</p
