The hydrodynamic behavior of the perfusion process (cleaning) of the liver endovascular before the operation was studied to provide a theoretical guidance to the relative operations. A straight and a curved first-class vascular entity model with foreign matter and the control equations of turbulence liquid in vessel was established. With the physical parameters of a medical infusion liquid measured, an estimation method of perfusion parameters as an example, the perfusion velocity was proposed. The simulation was performed by changing technical parameters of the perfusion. Based on the control equations of turbulent liquid in vessel and the preliminarily calculated results using the vessel model, the results fitted the values of the real operation. The simulation results showed clearly the fluid dynamics behavior around the foreign matter, for example the swirling flow. The results also showed the distribution of velocity of the fluid and the wall pressure of the vessels. With the increasing velocity of the entrance perfusion, the pressure and the velocity field were increased in the two types of the vessel model. The negative wall pressure and recirculation region appeared and located in the foreign matter. Because of influence of the shape, the fluid dynamics behavior in the curved vessel model was more complicated than that in the straight vessel model. The swirling flow and the phenomenon of stagnation of the perfusion fluid were more likely to appear in the curved vessel than in the straight vessel. The most important conclusion of this paper is that the appropriate perfusion velocity can be esti-mated using the methods proposed in this paper.
The geometric bone model of patients is an important basis for individualized biomechanical modeling and analysis, formulation of surgical planning, design of surgical guide plate, and customization of artificial joint. In this study, a rapid three-dimensional (3D) reconstruction method based on statistical shape model was proposed for femur. Combined with the patient plain X-ray film data, rapid 3D modeling of individualized patient femur geometry was realized. The average error of 3D reconstruction was 1.597–1.842 mm, and the root mean square error was 1.453–2.341 mm. The average errors of femoral head diameter, cervical shaft angle, offset distance and anteversion angle of the reconstructed model were 0.597 mm, 1.163°, 1.389 mm and 1.354°, respectively. Compared with traditional modeling methods, the new method could achieve rapid 3D reconstruction of femur more accurately in a shorter time. This paper provides a new technology for rapid 3D modeling of bone geometry, which is helpful to promote rapid biomechanical analysis for patients, and provides a new idea for the selection of orthopedic implants and the rapid research and development of customized implants.
The prevalence of cardiovascular disease in our country is increasing, and it has been a big problem affecting the social and economic development. It has been demonstrated that early intervention of cardiovascular risk factors can effectively reduce cardiovascular disease-caused mortality. Therefore, extensive implementation of cardiovascular testing and risk factor screening in the general population is the key to the prevention and treatment of cardiovascular disease. However, the categories of devices available for quick cardiovascular testing are limited, and in particular, many existing devices suffer from various technical problems, such as complex operation, unclear working principle, or large inter-individual variability in measurement accuracy, which lead to an overall low popularity and reliability of cardiovascular testing. In this study, we introduce the non-invasive measurement mechanisms and relevant technical progresses for several typical cardiovascular indices (e.g., peripheral/central arterial blood pressure, and arterial stiffness), with emphasis on describing the applications of biomechanical modeling and simulation in mechanism verification, analysis of influential factors, and technical improvement/innovation.
In the present study, a finite element model of L4-5 lumbar motion segment was established based on the CT images and a combination with image processing software, and the analysis of lumbar biomechanical characteristics was conducted on the proposed model according to different cases of flexion, extension, lateral bending and axial rotation. Firstly, the CT images of lumbar segment L4 to L5 from a healthy volunteer were selected for a three dimensional model establishment which was consisted of cortical bone, cancellous bone, posterior structure, annulus, nucleus pulposus, cartilage endplate, ligament and facet joint. The biomechanical analysis was then conducted according to different cases of flexion, extension, lateral bending and axial rotation. The results showed that the established finite element model of L4-5 lumbar segment was realistic and effective. The axial displacement of the proposed model was 0.23, 0.47, 0.76 and 1.02 mm, respectively under the pressure of 500, 1 000, 1 500 and 2 000 N, which was similar to the previous studies in vitro experiments and finite element analysis of other people under the same condition. The stress distribution of the lumbar spine and intervertebral disc accorded with the biomechanical properties of the lumbar spine under various conditions. The established finite element model has been proved to be effective in simulating the biomechanical properties of lumbar spine, and therefore laid a good foundation for the research of the implants of biomechanical properties of lumbar spine.
The subpulmonary ventricular exclusion (Fontan) could effectively improve the living quality for the children patients with a functional single ventricle in clinical. However, postoperative Fontan circulation failure can easily occur, causing obvious limitations while clinically implementing Fontan. The cavopulmonary assist devices (CPAD) is currently an effective means to solve such limitations. Therefore, in this paper the in-silico and in-vitro experiment coupled model of Fontan circulation failure for the children patients with a single ventricle and CPAD is established to evaluate the effects of CPAD on the Fontan circulation failure. Then a sensorless feedback control algorithm is proposed to provide sufficient cardiac output and prevent vena caval suction due to CPAD constant pump speed. Based on the CPAD pump speed-an intrinsic parameter, the sensorless feedback control algorithm could accurately estimate the cavopulmonary pressure head (CPPH) using extended Kalman filter, eliminating the disadvantage for pressure sensors that cannot be used in long term. And a gain-scheduled, proportional integral (PI) controller is used to make the actual CPPH approach to the reference value. Results show that the CPAD could effectively increase physiological perfusion for the children patients and reduce the workload of a single ventricle, and the sensorless feedback control algorithm can effectively guarantee cardiac output and prevent suction. This study can provide theoretical basis and technical support for the design and optimization of CPAD, and has potential clinical application value.
A method of ultrasonic simulation based on the FIELD II software platform for carotid artery plaque was proposed according to the analysis for geometrical shape, tissue characteristics and acoustic properties of carotid artery plaques in clinic, and then a simulation system was developed by using the MATLAB graphical user interface (GUI). In the simulation and development, a three-dimensional geometric model of blood vessel with plaques was set up by using the metaball implicit surface technique, and a tissue model was established based on the scatterers with spatial position of gamma random distribution. Comparison of the statistical and geometrical characteristics from simulated ultrasound B-mode images with those based on clinical ones and preset values, the results fully demonstrated the effectiveness of the simulation methods and system.
It is very difficult for stroke patients to complete the action of squatting-standing because their equilibrium function ability has been seriously declined. It was necessary, therefore, to do a deep research on the action of human squatting-standing and to set up an accurate model and simulation. In our modeling research, the movements of upper limbs and head was neglected, and a seven-segment model was developed to establish the coordinate system of human squatting-standing action. It calculated the knee joint moment and hip joint moment during squatting and standing by utilizing Lagrange method, and then simulated this mathematical model by utilizing Matlab. Geometric model of human squatting-standing was developed and simulated in ADAMS which proved that the established Lagrange model was reasonable. It would also provide significant theoretical references for further study and development of squatting-standing rehabilitation training equipment.
ObjectiveSystemic lupus erythematosus (SLE) patients from a SLE family with homogeneity can provide experimental basis for individualized diagnosis and treatment by studying the characteristics of laboratory tests and symptoms. MethodsLaboratory tests were analyzed for three SLE patients in the family, and set up the screen model by three laboratory tests (anitnuclear antibody positive, rheumatoid factor positive and IgE positive, ANA+RF+IgE+). All SLE cases were screened from latest four years as SLE subtype patients (named "similar family SLE patients"), then the family laboratory tests and clinical characteristics were analyzed. ResultsA total of 55 patients (6.27%) were screened as similar family SLE patients from individual SLE patients according to model from 877 cases. The laboratory tests of similar family SLE patients including creatinine, WBC, CRP were significant lower than other SLE patients (P < 0.05), but significant higher for the IgG, positive rate of anti-SSA and anti-SSB (P < 0.05), and the alopecia and skin rashes were more common in similar family SLE patients than other SLE patients. ConclusionsThe ANA+RF+IgE+ SLE patients are of lower inflammatory state and kidney involvement; Clinical symptom is priority to alopecia and skin rashes.
The human skeletal muscle drives skeletal movement through contraction. Embedding its functional information into the human morphological framework and constructing a digital twin of skeletal muscle for simulating physical and physiological functions of skeletal muscle are of great significance for the study of "virtual physiological humans". Based on relevant literature both domestically and internationally, this paper firstly summarizes the technical framework for constructing skeletal muscle digital twins, and then provides a review from five aspects including skeletal muscle digital twins modeling technology, skeletal muscle data collection technology, simulation analysis technology, simulation platform and human medical image database. On this basis, it is pointed out that further research is needed in areas such as skeletal muscle model generalization, accuracy improvement, and model coupling. The methods and means of constructing skeletal muscle digital twins summarized in the paper are expected to provide reference for researchers in this field, and the development direction pointed out can serve as the next focus of research.
The present paper proposed a central-driven structure of upper limb rehabilitation robot in order to reduce the volume of the robotic arm in the structure, and also to reduce the influence of motor noise, radiation and other adverse factors on upper limb dysfunction patient. The forward and inverse kinematics equations have been obtained with using the Denavit-Hartenberg (D-H) parameter method. The motion simulation has been done to obtain the angle-time curve of each joint and the position-time curve of handle under setting rehabilitation path by using SolidWorks software. Experimental results showed that the rationality with the central-driven structure design had been verified by the fact that the handle could move under setting rehabilitation path. The effectiveness of kinematics equations had been proved, and the error was less than 3°by comparing the angle-time curves obtained from calculation with those from motion simulation.