Test Method Development for Evaluation of Process and Design Effect on Reinforced Tube

Authors: Cathal Merz, Gareth O’Donnell

Abstract:

Coil reinforced thin-walled (CRTW) tubes are used in medicine to treat problems affecting blood vessels within the body through minimally invasive procedures. The CRTW tube considered in this research makes up part of such a device and is inserted into the patient via their femoral or brachial arteries and manually navigated to the site in need of treatment. This procedure replaces the requirement to perform open surgery but is limited by reduction of blood vessel lumen diameter and increase in tortuosity of blood vessels deep in the brain. In order to maximize the capability of these procedures, CRTW tube devices are being manufactured with decreasing wall thicknesses in order to deliver treatment deeper into the body and to allow passage of other devices through its inner diameter. This introduces significant stresses to the device materials which have resulted in an observed increase in the breaking of the proximal segment of the device into two separate pieces after it has failed by buckling. As there is currently no international standard for measuring the mechanical properties of these CRTW tube devices, it is difficult to accurately analyze this problem. The aim of the current work is to address this discrepancy in the biomedical device industry by developing a measurement system that can be used to quantify the effect of process and design changes on CRTW tube performance, aiding in the development of better performing, next generation devices. Using materials testing frames, micro-computed tomography (micro-CT) imaging, experiment planning, analysis of variance (ANOVA), T-tests and regression analysis, test methods have been developed for assessing the impact of process and design changes on the device. The major findings of this study have been an insight into the suitability of buckle and three-point bend tests for the measurement of the effect of varying processing factors on the device’s performance, and guidelines for interpreting the output data from the test methods. The findings of this study are of significant interest with respect to verifying and validating key process and design changes associated with the device structure and material condition. Test method integrity evaluation is explored throughout.

Keywords: Buckling, coil reinforced thin-walled tubes, fracture, test method.

Digital Object Identifier (DOI): doi.org/10.6084/m9.figshare.12488981

References:

[1] R. Hijikata, T. Shiraiwa, M. Enoki, K. Matsubara, and K. Tokumoto, "Evaluation of Mechanical Properties of Catheter Shafts under Cyclic Bending," Materials Transactions, vol. 58, no. 7, 2017.
[2] The Madison Group, "Fractographic Evaluation of Three Catheter xtrusions ", 2019.
[3] J. A. Jansen. (2015) Plastics Failure through Molecular Degradation. Plastics Engineering. 1-2. Available: http://read.nxtbook.com/wiley/plasticsengineering/january2015/consultantscorner.html
[4] F. L. Gonzalez, F. C. Albuquerque, and C. G. McDougall, Neurointerventional Techniques: Tricks of the Trade. Thieme Medical Publishers, Incorporated, 2019.
[5] S. Leanard. "Key Considerations for Designing Neurovascular Microcatheters." https://www.mddionline.com/key-considerations-designing-neurovascular-microcatheters (accessed 04 Dec, 2019).
[6] Creganna Medical. "Engineering Corner." http://www.creganna.com/resources/engineering-corner/ (accessed 05 Dec, 2019).
[7] R. Roth. (2001) Design Considerations in Small-Diameter Medical Tubing. Medical Device & Diagnostic Industry Magazine. Available: https://www.mddionline.com/design-considerations-small-diameter-medical-tubing
[8] C. L. Shields, A. Ramasubramanian, R. Rosenwasser, and J. A. Shields, "Superselective Catheterization of the Ophthalmic Artery for Intraarterial Chemotherapy for Retinoblastoma," Retina the Journal of Retinal and Vitreous Diseases, vol. 29, pp. 1207-1209, 2009.
[9] Foster Biomedical Polymers and Compounds. "Catheter Pushability and Navigation." https://www.fostercomp.com/catheter-pushability-and-navigation/ (accessed 06 Dec, 2019).
[10] S. P. Timoshenko, "Theory of Elastic Stability," J. M. Gere, Ed., 2nd ed: McGraw-Hill International Book Company, 1963.
[11] L. G. Brazier, "On the Flexure of Thin Cylindrical Shells and other "Thin" Sections," Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character, 1927.
[12] H. Shima, M. Satoro, and S. Park, "Suppression of Brazier Effect in Multi-Layered Cylinders," Advances in Condensed Matter Physics, vol. 2014, 2014.
[13] J. D. A. Bailly, O. Laccoureye, A. Laurent and J. J. Merland, "Mechanical properties of catheters: Designing of tests for kinking, traction, and torsion and their validation on a series of central venous catheters," 1992 14th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, pp. 1162-1163, 1992.
[14] ISO 10619-1:2017 Rubber and plastics hoses and tubing - Measurement of flexibility and stiffness - Part 1: Bending tests at ambient temperature, I. O. f. Standardization, Geneva, Switzerland, 2017.
[15] ISO 178:2019 Plastics - Determination of flexural properties, I. O. f. Standardization, Geneva, Switzerland, 2019.
[16] Plastics — Determination of tensile properties — Part 2: Test conditions for moulding and extrusion plastics, I. O. f. Standardization, Geneva, Switzerland, 2012.
[17] IBM. "One-Way ANOVA Post-Hoc Tests." https://www.ibm.com/support/knowledgecenter/en/SSLVMB_24.0.0/spss/base/idh_onew_post.html (accessed 10 Jan, 2020).
[18] Laerd Statistics. "One-way ANOVA (cont...)." https://statistics.laerd.com/statistical-guides/one-way-anova-statistical-guide-2.php (accessed 13 Jan, 2020).
[19] Y. Khan, R. Narayam, Ed. Encyclopedia of Biomedical Engineering 2019. Elsevier, 2019.