Reverse shock index multiplied by Glasgow coma scale as a predictor of massive transfusion in trauma.

BACKGROUND AND PURPOSE: Previous studies have identified that the reverse shock index multiplied by the Glasgow Coma Scale score (rSIG) is a good predictor of mortality in trauma patients. However, it is unknown if rSIG has utility as a predictor for massive transfusion (MT) in trauma patients. The present study evaluated the ability of rSIG to predict MT in trauma patients. METHODS: This was a retrospective, observational study performed at a level 1 trauma center. Consecutive patients who presented to the trauma center emergency department between January 2016 and December 2018 were included. The predictive ability of rSIG for MT was assessed as our primary outcome measure. Our secondary outcome measures were the predictive ability of rSIG for coagulopathy, in-hospital mortality, and 24-h mortality. We compared the prognostic performance of rSIG with the shock index, age shock index, and quick Sequential Organ Failure Assessment. RESULTS: In total, 1627 patients were included and 117 (7.2%) patients received MT. rSIG showed the highest area under the receiver operating characteristic (AUROC) curve (0.842; 95% confidence interval [CI], 0.806--0.878) for predicting MT. rSIG also showed the highest AUROC for predicting coagulopathy (0.769; 95% CI, 0.728-0.809), in-hospital mortality (AUROC 0.812; 95% CI, 0.772-0.852), and 24-h mortality (AUROC 0.826; 95% CI, 0.789-0.864). The sensitivity of rSIG for MT was 0.79, and the specificity of rSIG for MT was 0.77. All tools had a high negative predictive value and low positive predictive value. CONCLUSION: rSIG is a useful, rapid, and accurate predictor for MT, coagulopathy, in-hospital mortality, and 24- h mortality in trauma patients.

Investigating the influence of collagen cross-linking on mechanical properties of thoracic aortic tissue.

Vascular diseases, such as abdominal aortic aneurysms, are associated with tissue degeneration of the aortic wall, resulting in variations in mechanical properties, such as tissue ultimate stress and a high slope. Variations in the mechanical properties of tissues may be associated with an increase in the number of collagen cross-links. Understanding the effect of collagen cross-linking on tissue mechanical properties can significantly aid in predicting diseased aortic tissue rupture and improve the clarity of decisions regarding surgical procedures. Therefore, this study focused on increasing the density of the aortic tissue through cross-linking and investigating the mechanical properties of the thoracic aortic tissue in relation to density. Uniaxial tensile tests were conducted on the porcine thoracic aorta in four test regions (anterior, posterior, distal, and proximal), two loading directions (circumferential and longitudinal), and density increase rates (0%-12%). As a result, the PPC (Posterior/Proximal/Circumferential) group experienced a higher ultimate stress than the PDC (Posterior/Distal/Circumferential) group. However, this relationship reversed when the specimen density exceeded 3%. In addition, the ultimate stress of the ADC (Anterior/Distal/Circumferential) and PPC group was greater than that of the APC (Anterior/Proximal/Circumferential) group, while these findings were reversed when the specimen density exceeded 6% and 9%, respectively. Finally, the high slope of the PDL (Posterior/Distal/Longitudinal) group was lower than that of the ADL (Anterior/Distal/Longitudinal) group, but the high slope of the PDL group appeared larger due to the stabilization treatment. This highlights the potential impact of density variations on the mechanical properties of specific specimen groups.

Predictive factors for size change of aorta in patients with acute blunt traumatic aortic injury.

OBJECTIVE: We aimed to investigate the changes in aorta size, the factors affecting size changes in patients with acute blunt traumatic aortic injury and to evaluate the adequacy of the current 120% thoracic endovascular aortic repair graft oversizing policy. DESIGN AND METHODS: This retrospective review study was conducted using the prospectively collected medical records of 45 patients (mean age: 53.5 years, male: 39 patients) with blunt traumatic aortic injury treated at a level 1 trauma center between 2012 and 2021. Aortic diameter was measured by computed tomography angiographic images at four different levels [ascending aorta (A), isthmus (B), descending thoracic aorta (C), and infrarenal aorta (D)] on arrival and follow-up (median time interval, 13 days). Associated factors including patient characteristics and hemodynamic parameters on arrival and follow-up were collected to determine their influence on changes in the aorta. RESULTS: The mean diameter of all four aortic levels increased on follow-up computed tomography compared to initial computed tomography (A: + 11.77%, B: + 10.19%, C: + 7.71%, D: + 12.04%). Patient age and injury severity score influenced changes in the diameter of the ascending aorta (P < 0.05). Patient age and blunt traumatic aortic injury grade were significantly associated with changes in the infrarenal aortic diameter (P < 0.05). Three cases of type 1 endoleak were observed at follow-up but all were spontaneously resolved without further intervention at next computed tomography follow-up. CONCLUSIONS: In patients with acute blunt traumatic aortic injury, aortic diameter is significantly smaller by about 10% under shock and is not considered a basis for oversizing the currently implemented 120% thoracic endovascular aortic repair graft sizing. However, in young patients under the age of 40, the change is significantly large and subsequent computed tomography follow-up is required.

A novel in silico Nuss procedure for pectus excavatum patients.

The purpose of this study is to suggest a novel in silico Nuss procedure that can predict the results of chest wall deformity correction. Three-dimensional (3D) geometric and finite element model of the chest wall were built from the 15-year-old male adolescent patient's computed tomography (CT) image with pectus excavatum of the mild deformity. A simulation of anterior translating the metal bar (T) and a simulation of maintaining equilibrium after 180-degree rotation (RE) were performed respectively. A RE simulation using the chest wall finite element model with intercostal muscles (REM) was also performed. Finally, the quantitative results of each in silico Nuss procedure were compared with those of postoperative patient. Furthermore, various mechanical indicators were compared between simulations. This confirmed that the REM simulation results were most similar to the actual patient's results. Through two clinical indicators that can be compared with postoperative patient and mechanical indicators, the authors consider that the REM of silico Nuss procedure proposed in this study is best simulated the actual surgery.

Factors related to steroid treatment responsiveness in thyroid eye disease patients and application of SHAP for feature analysis with XGBoost.

Introduction: The primary treatment for active thyroid eye disease (TED) is immunosuppressive therapy with intravenous steroids. In this study, we attempted to predict responsiveness to steroid treatment in TED patients using eXtreme Gradient Boosting (XGBoost). Factors associated with steroid responsiveness were also statistically evaluated. Methods: Clinical characteristics and laboratory results of 89 patients with TED who received steroid treatment were retrospectively reviewed. XGBoost was used to explore responsiveness to steroid treatment, and the diagnostic performance was evaluated. Factors contributing to the model output were investigated using the SHapley Additive exPlanation (SHAP), and the treatment response was investigated statistically using SPSS software. Results: The eXtra Gradient Boost model showed high performance, with an excellent accuracy of 0.861. Thyroid-stimulating hormone, thyroid-stimulating immunoglobulin (TSI), and low-density lipoprotein (LDL) cholesterol had the highest impact on the model. Multivariate logistic regression analysis showed that less extraocular muscle limitation and high TSI levels were associated with a high risk of poor intravenous methylprednisolone treatment response. As a result of analysis through SHAP, TSH, TSI, and LDL had the highest impact on the XGBoost model. Conclusion: TSI, extraocular muscle limitation, and LDL cholesterol levels may be useful in predicting steroid treatment response in patients with TED. In terms of machine learning, XGBoost showed relatively robust and reliable results for small datasets. The machine-learning model can assist in decision-making for further treatment of patients with TED.

Identification of screw spacing on pediatric hip locking plate in proximal femoral osteotomy.

This study describes a computational analysis technique for evaluating the effect of screw spacing and angle on the pediatric hip locking plate system in proximal femoral osteotomy in pediatric patients having DDH with an aberrant femoral head and femoral angle. Under static compressive load conditions, the stresses of the screw and bone were examined as the screw spacing and angle changed. The spacing and angle of various screws were specifically considered as variables in this study based on the pile mechanism studied in civil engineering. As with the group pile mechanism, the tighter the screw spacing under static compressive loads, the more the overlapping effect between the bone stresses and the screws develops, increasing the risk of injuring the patient's bone. Therefore, a series of simulations was performed to determine the optimal screw spacing and angles to minimize the overlapping effect of bone stress. In addition, a formula for determining the minimum screw spacing was proposed based on the computational simulation results. Finally, if the outcomes of this study are applied to pediatric patients with DDH in the pre-proximal femoral osteotomy stage, post-operative load-induced femur damage will be reduced.

A novel computer modeling and simulation technique for bronchi motion tracking in human lungs under respiration.

In this work, we proposed a novel computer modeling and simulation technique for motion tracking of lung bronchi (or tumors) under respiration using 9 cases of computed tomography (CT)-based patient-specific finite element (FE) models and Ogden's hyperelastic model. In the fabrication of patient-specific FE models for the respiratory system, various organs such as the mediastinum, diaphragm, and thorax that could affect the lung motions during breathing were considered. To describe the nonlinear material behavior of lung parenchyma, the comparative simulation for biaxial tension-compression of lung parenchyma was carried out using several hyperelastic models in ABAQUS, and then, Ogden's model was adopted as an optimal model. Based on the aforementioned FE models and Ogden's material model, the 9 cases of respiration simulation were carried out from exhalation to inhalation, and the motion of lung bronchi (or tumors) was tracked. In addition, the changes in lung volume, lung cross-sectional area on the axial plane during breathing were calculated. Finally, the simulation results were quantitatively compared to the inhalation/exhalation CT images of 9 subjects to validate the proposed technique. Through the simulation, it was confirmed that the average relative errors of simulation to clinical data regarding to the displacement of 258 landmarks in the lung bronchi branches of total subjects were 1.10%~2.67%. In addition, the average relative errors of those with respect to the lung cross-sectional area changes and the volume changes in the superior-inferior direction were 0.20%~5.00% and 1.29 ~ 9.23%, respectively. Hence, it was considered that the simulation results were coincided well with the clinical data. The novelty of the present study is as follows: (1) The framework from fabrication of the human respiratory system to validation of the bronchi motion tracking is provided step by step. (2) The comparative simulation study for nonlinear material behavior of lung parenchyma was carried out to describe the realistic lung motion. (3) Various organs surrounding the lung parenchyma and restricting its motion were considered in respiration simulation. (4) The simulation results such as landmark displacement, lung cross-sectional area/volume changes were quantitatively compared to the clinical data of 9 subjects.

Identification of optimal surgical plan for treatment of extraocular muscle damage in thyroid eye disease patients based on computational biomechanics.

This study replicated the behavior of intraorbital tissue in patients with thyroid eye disease (TED) based on finite element analysis for general orbital decompression risk evaluation in thyroid eye disease patients. The orbit and intraorbital tissues of thyroid eye disease patients who underwent orbital decompression were modeled as finite element models. The stress was examined at specific locations of the removed orbital wall of a thyroid eye disease patient with undergone orbital decompression, and its variation was analyzed as a function of the shape and dimension (to be removed). As a result, in orbital decompression surgery which removes the orbital wall in a rectangular shape, the stress at the orbital wall decreased as the width and depth of the removed orbital wall increased. In addition, in the case of orbital decompression, it can be seen that the chamfered model compared to the non-chamfered model (a form of general orbital decompression) have the stress reduction rate from 11.08% to 97.88%. It is inferred that if orbital decompression surgery considering the chamfered model is performed on an actual thyroid eye disease patient, it is expected that the damage to the extraocular muscle caused by the removed orbital wall will be reduced.

Stress Distribution on Spinal Cord According to Type of Laminectomy for Large Focal Cervical Ossification of Posterior Longitudinal Ligament Based on Finite Element Method.

Most studies on the ossification of the posterior longitudinal ligament (OPLL) using the finite element method were conducted in the neutral state, and the resulting decompression was judged to be good. As these studies do not reflect the actual behavior of the cervical spine, this study conducted an analysis in the neutral state and a biomechanical analysis during flexion and extension behaviors. After validation via the construction of an intact cervical spine model, the focal OPLL model was inserted into the C4-C5 segment and a simulation was performed. The neutral state was shown by applying a fixed condition to the lower part of the T1 and Y-axis fixed condition of the spinal cord and simulating spinal cord compression with OPLL. For flexion and extension simulation, a ±30-degree displacement was additionally applied to the top of the C2 dens. Accordingly, it was confirmed that spinal cord decompression did not work well during the flexion and extension behaviors, but rather increased. Thus, if patients with focal OPLL inevitably need to undergo posterior decompression, additional surgery using an anterior approach should be considered.

Region-dependent mechanical characterization of porcine thoracic aorta with a one-to-many correspondence method to create virtual datasets using uniaxial tensile tests.

The simulation of the cardiovascular system and in silico clinical trials have garnered attention in the biomedical engineering field. Physics-based modeling is essential to associate with physical and clinical features. In physics-based constitutive modeling, the identification of the parameters and estimation of their ranges based on appropriate experiments are required. Uniaxial tests are commonly used in the field of vascular mechanics, but they have limitations in fully characterizing the regional mechanical behavior of the aorta. Therefore, this study is aimed at identifying a method to integrate constitutive models with experimental data to elucidate regional aortic behavior. To create a virtual two-dimensional dataset, a pair of uniaxial experimental datasets in the longitudinal and circumferential directions was combined using a one-to-many correspondence method such as bootstrap aggregation. The proposed approach is subsequently applied to three constitutive models, i.e., the Fung model, Holzapfel model, and constrained mixture model, to estimate the material parameters based on the four test regions of the porcine thoracic aorta. Finally, the regional difference in the mechanical behavior of the aorta, the correlation between the experimental characteristics and model parameters, and the inter-correlation of the material parameters are confirmed. This integrative approach will enhance the prediction capability of the model with respect to the regions of the aorta.

Spinal stability analysis of lumbar interbody fusion according to pelvic type and cage angle based on simplified spinal model with various pelvic indices.

Recently, the objectives of lumbar interbody fusion (LIF) have been extended to include the correction of broader/relative indications in addition to spinal fixation. Accordingly, LIF must be optimized for sagittal alignment while simultaneously achieving decompression. Therefore, a representative model classified into three pelvic types, i.e., neutral pelvis (NP), anterior pelvis (AP), and retroverted pelvis (RP), was selected according to the pelvic index, and LIF was performed on each representative model to analyze Lumbar lordosis (LL) and the corresponding equivalent stress. The finite element (FE) model was based on a sagittal 2D X-ray image. The calculation efficiency and convergence were improved by simplifying the modeling of the vertebral body in general and its posterior portion in particular. Based on the position of the pelvis, according to the pelvic shape, images of patients were classified into three types: AP, RP, and NP. Subsequently, representative images were selected for each type. The fixation device used in the fusion model was a pedicle screw and a spinal rod of a general type. PEEK was used as the cage material, and the cage shape was varied by using three different cage angles: 0°, 4°, and 8°. Spinal mobility: The pelvic type with the highest range of motion (ROM) for the spine was the NP type; the AP type had the highest LL. Under a combination load, the NP type exhibited the highest lumbar flexibility (LF), which was 2.46° lower on average compared to the case where a pure moment was applied. Equivalent stress on the spinal fixation device: The equivalent stress acting on the vertebrae was lowest when cage 0 was used for the NP and AP type. For the RP type, the lowest equivalent stress on the vertebrae was observed when cage 4 was used. Finally, for the L5 upper endplate, the stress did not vary significantly for a given type of cage. In conclusion, there was no significant difference in ROM according to cage angle, and the highest ROM, LL and LF were shown in the pelvic shape of NP type. However, when comparing the results with other pelvic types, it was not possible to confirm that LF is completely dependent on LL and ROM.