Vulnerability of different nerves to intrafascicular injection by different needle types and at different approach angles: a mathematical model

2020 ◽  
Vol 45 (4) ◽  
pp. 306-310
Author(s):  
Margarita Sanromán-Junquera ◽  
Andre Boezaart ◽  
Yury Zasimovich ◽  
Olga C Nin ◽  
Xavier Sala-Blanch ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Cross Sections ◽  
Longitudinal Axis ◽  
Needle Insertion ◽  
Nerve Roots ◽  
Nerve Blocks ◽  
Cross Sectional ◽  
Peripheral Nerve Blocks ◽  
Microscopic Images ◽  
Insertion Angle

Background and objectivesWe assume that intrafascicular spread of a solution can only occur if a large enough portion of the distal needle orifice is placed inside the fascicle. Our aim is to present and evaluate a mathematical model that can calculate the theoretical vulnerability of fascicles, analyzing the degree of occupancy of the needle orifice in fascicular tissue by performing simulations of multiple positions that a needle orifice can take inside a cross-sectional nerve area.MethodsWe superimposed microscopic images of two routinely used nerve block needles (22-gauge, 15° needle and 22-gauge, 30° needle) over the microscopic images of cross-sections of four nerve types photographed at the same magnification. Fascicular tissue that was overlapped between 80% and 100% by a needle orifice was considered at risk to possible intrafascicular injection. The effect of three angular approaches was evaluated.ResultsThere were statistical differences between the vulnerability of fascicular tissue depending on nerve type, the bevel angle of the needle and the angle approach. Fascicular vulnerability was greater in nerve roots of the brachial plexus after using a 22-gauge 30° needle, as was choosing a 45° angle approach to the longitudinal axis of the nerve.ConclusionsOur results suggest that clinicians may want to consider needle insertion angle and bevel type as they perform peripheral nerve blocks. Furthermore, researchers may want to consider this mathematical model when estimating vulnerabilities of various nerves, needle types and angles of approach of needles to nerves.

Analytical solutions of thermo-piezoelectric interactions in a solid fiber of polygonal cross-sections immersed in fluid

2018 ◽  
Vol 14 (3) ◽  
pp. 431-456
Author(s):  
Rajendran Selvamani
Keyword(s):  
Mathematical Model ◽  
Phase Velocity ◽  
Cross Sections ◽  
Analytical Solutions ◽  
Fourier Expansion ◽  
Transversely Isotropic ◽  
Cross Sectional ◽  
Content Type ◽  
Phase Velocity And Attenuation ◽  
Frequency Phase

Purpose The purpose of this paper is to study the analytical solutions of transversely isotropic thermo-piezoelectric interactions in a polygonal cross-sectional fiber immersed in fluid using the Fourier expansion collocation method. Design/methodology/approach A mathematical model is developed for the analytical study on a transversely isotropic thermo-piezoelectric polygonal cross-sectional fiber immersed in fluid using a linear form of three-dimensional piezothermoelasticity theories. After developing the formal solution of the mathematical model consisting of partial differential equations, the frequency equations have been analyzed numerically by using the Fourier expansion collocation method (FECM) at the irregular boundary surfaces of the polygonal cross-sectional fiber. The roots of the frequency equation are obtained by using the secant method, applicable for complex roots. Findings From the literature survey, it is evident that the analytical formulation of thermo-piezoelectric interactions in a polygonal cross-sectional fiber contact with fluid is not discussed by any researchers. Also, in this study, a polygonal cross-section is used instead of the traditional circular cross-sections. So, the analytical solutions of transversely isotropic thermo-piezoelectric interactions in a polygonal cross-sectional fiber immersed in fluid are studied using the FECM. The dispersion curves for non-dimensional frequency, phase velocity and attenuation coefficient are presented graphically for lead zirconate titanate (PZT-5A) material. The present analytical method obtained by the FECM is compared with the finite element method which shows a good agreement with present study. Originality/value This paper contributes the analytical model to find the solution of transversely isotropic thermo-piezoelectric interactions in a polygonal cross-sectional fiber immersed in fluid. The dispersion curves of the non-dimensional frequency, phase velocity and attenuation coefficient are more prominent in flexural modes. Also, the surrounding fluid on the various considered wave characteristics is more significant and dispersive in the hexagonal cross-sections. The aspect ratio (a/b) of polygonal cross-sections is critical to industry or other fields which require more flexibility in design of materials with arbitrary cross-sections.

scholarly journals Effect of Microneedle Cross-Sectional Shape on Puncture Resistance – Investigation of Polygonal and Star-Shaped Cross Sections –

2020 ◽  
Vol 32 (2) ◽  
pp. 371-381
Author(s):  
Seiji Aoyagi ◽  
Kento Okuda ◽  
Tomokazu Takahashi ◽  
Masato Suzuki ◽  
◽  
...  
Keyword(s):  
Cross Sections ◽  
Frictional Resistance ◽  
Needle Insertion ◽  
Medical Field ◽  
Cross Sectional ◽  
Puncture Resistance ◽  
Laser Lithography ◽  
Maximum Resistance ◽  
Sharp Edges ◽  
Sectional Shape

The shape of the needle tip that is currently used in the medical field is a “lancet point,” which is a diagonally cut cylindrical pipe, further cut on both sides. The shape of the needle shank is typically cylindrical. In this paper, tip and shank shapes that differ from the standard shape are experimentally investigated for the purpose of reducing puncture resistance. Microneedles of various cross-sectional shapes, such as polygonal and star-like, were fabricated using stereo laser lithography. Before the needle penetrates the skin, sharp edges at the needle tip may be effective to generate a stress concentration on the skin, inducing a skin fracture. After the needle penetrates the skin, corners in the cross section of the needle shank may effectively reduce the frictional resistance because the contact area between the skin and needle is limited at the corners. A needle insertion experiment was conducted against an artificial skin made of polydimethylsiloxane. The puncture resistance decreased respectively for the circular needle, polygonal needle, and star-shaped needle. For the star-shaped needles, the maximum resistance decreased as the number of corners (N) decreased. For the polygonal needle, the maximum resistance increased as N increased from 3 to 5; however, there was no observable difference for N from 6 to 8. The experimental results show that a triangular star-shaped microneedle is the most effective in reducing the puncture resistance.

scholarly journals Cross-Sectional Performance of Hollow Square Prisms with Rounded Edges

Symmetry ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 996
Author(s):  
Hiroyuki Shima ◽  
Nao Furukawa ◽  
Yuhei Kameyama ◽  
Akio Inoue ◽  
Motohiro Sato
Keyword(s):  
Mechanical Properties ◽  
Mathematical Model ◽  
Cross Sections ◽  
Cross Sectional ◽  
Hollow Section ◽  
Buckling Resistance ◽  
The Cross ◽  
The Stability ◽  
External Forces ◽  
Sectional Shape

Hollow-section columns are one of the mechanically superior structures with high buckling resistance and high bending stiffness. The mechanical properties of the column are strongly influenced by the cross-sectional shape. Therefore, when evaluating the stability of a column against external forces, it is necessary to reproduce the cross-sectional shape accurately. In this study, we propose a mathematical method to describe a polygonal section with rounded edges and vertices. This mathematical model would be quite useful for analyzing the mechanical properties of plants and designing plant-mimicking functional structures, since the cross-sections of the actual plant culms and stems often show rounded polygons.

scholarly journals Variability in determination of point of needle insertion in peripheral nerve blocks: A comparison of experienced and inexperienced anaesthetists

Anaesthesia ◽  
2003 ◽  
Vol 58 (7) ◽  
pp. 688-692 ◽  
Author(s):  
S. A. Grant ◽  
D. S. Breslin ◽  
D. B. MacLeod ◽  
D. Demeyts ◽  
G. Martin ◽  
...  
Keyword(s):  
Peripheral Nerve ◽  
Needle Insertion ◽  
Nerve Blocks ◽  
Peripheral Nerve Blocks

Gender determination of caucasoid hair using image analysis

1993 ◽  
Vol 51 ◽  
pp. 216-217
Author(s):  
T.B. Ball ◽  
W.M. Hess
Keyword(s):  
Image Analysis ◽  
Cross Sections ◽  
Scalp Hair ◽  
The Body ◽  
Equivalent Diameter ◽  
Cross Sectional ◽  
Hair Samples ◽  
Length Width ◽  
Morphological Differences

It has been demonstrated that cross sections of bundles of hair can be effectively studied using image analysis. These studies can help to elucidate morphological differences of hair from one region of the body to another. The purpose of the present investigation was to use image analysis to determine whether morphological differences could be demonstrated between male and female human Caucasian terminal scalp hair.Hair samples were taken from the back of the head from 18 caucasoid males and 13 caucasoid females (Figs. 1-2). Bundles of 50 hairs were processed for cross-sectional examination and then analyzed using Prism Image Analysis software on a Macintosh llci computer. Twenty morphological parameters of size and shape were evaluated for each hair cross-section. The size parameters evaluated were area, convex area, perimeter, convex perimeter, length, breadth, fiber length, width, equivalent diameter, and inscribed radius. The shape parameters considered were formfactor, roundness, convexity, solidity, compactness, aspect ratio, elongation, curl, and fractal dimension.

Acute pain management in trauma: anatomy, ultrasound-guided peripheral nerve blocks and special considerations

2019 ◽  
Vol 85 (7) ◽  
Author(s):  
Theodosios Saranteas ◽  
Iosifina Koliantzaki ◽  
Olga Savvidou ◽  
Marina Tsoumpa ◽  
Georgia Eustathiou ◽  
...  
Keyword(s):  
Pain Management ◽  
Peripheral Nerve ◽  
Acute Pain ◽  
Ultrasound Guided ◽  
Acute Pain Management ◽  
Nerve Blocks ◽  
Peripheral Nerve Blocks

Fascial plane blocks and peripheral nerve blocks: two planets not so far apart

2019 ◽  
Vol 85 (10) ◽  
Author(s):  
Pierfrancesco Fusco ◽  
Eugenio Di Martino ◽  
Giuseppe Paladini ◽  
Francesca De Sanctis ◽  
Stefano Di Carlo ◽  
...  
Keyword(s):  
Peripheral Nerve ◽  
Nerve Blocks ◽  
Peripheral Nerve Blocks ◽  
Fascial Plane

Automated 3D measurement of fiber cross section morphology in handsheets

2012 ◽  
Vol 27 (2) ◽  
pp. 264-269 ◽  
Author(s):  
Christian Lorbach ◽  
Ulrich Hirn ◽  
Johannes Kritzinger ◽  
Wolfgang Bauer
Keyword(s):  
Image Analysis ◽  
Cross Section ◽  
Cross Sections ◽  
Image Plane ◽  
3D Measurement ◽  
Cross Sectional ◽  
Fiber Cross Section ◽  
Fiber Wall ◽  
Sectional Shape ◽  
Cross Section Geometry

Abstract We present a method for 3D measurement of fiber cross sectional morphology from handsheets. An automated procedure is used to acquire 3D datasets of fiber cross sectional images using an automated microtome and light microscopy. The fiber cross section geometry is extracted using digital image analysis. Simple sample preparation and highly automated image acquisition and image analysis are providing an efficient tool to analyze large samples. It is demonstrated that if fibers are tilted towards the image plane the images of fiber cross sections are always larger than the true fiber cross section geometry. In our analysis the tilting angles of the fibers to the image plane are measured. The resulting fiber cross sectional images are distorted to compensate the error due to fiber tilt, restoring the true fiber cross sectional shape. We use an approximated correction, the paper provides error estimates of the approximation. Measurement results for fiber wall thickness, fiber coarseness and fiber collapse are presented for one hardwood and one softwood pulp.

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