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1.0 INTRODUCTION 2.0 OBJECTIVE A Study of Changes in Mechanical Properties of Hernia Mesh Material After Exposure to Concentrated Acids Kayla Stevens Nicholas.

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Presentation on theme: "1.0 INTRODUCTION 2.0 OBJECTIVE A Study of Changes in Mechanical Properties of Hernia Mesh Material After Exposure to Concentrated Acids Kayla Stevens Nicholas."— Presentation transcript:

1 1.0 INTRODUCTION 2.0 OBJECTIVE A Study of Changes in Mechanical Properties of Hernia Mesh Material After Exposure to Concentrated Acids Kayla Stevens Nicholas Rusin Professor Janet Brady, Advisor Philadelphia University, The Kanbar College of Design, Engineering and Commerce 4.0 RESULTS AND DISCUSSION 3.0 MATERIALS AND METHODS 5.0 CONCLUSIONS & FUTURE WORK 6.0 REFERENCES ACKNOWLEDGMENTS Research in the medical community and in the pharmacology field verifies the correlation between peptic ulcers (holes forming in the internal organs along the gastro-intestinal track due to high acid levels) and unregulated, excessive dosages of Ibuprofen and Aspirin. Theoretically, the presence of a peptic ulcer could provide a transport mechanism that allows high levels of strong stomach acids (pH of 1.5) to enter into the body and have direct contact with other internal organs and biomaterials possibly disrupting bio-activities and eroding their tissues. This study will examine the mechanical changes, if any, after non-absorbable hernia mesh is exposed to a strong simulated stomach acid. The major health risk associated with peptic ulcers is that their presence allows gastric acid to flow freely into the body and come in contact with other tissues and biomaterials (such as hernia mesh) potentially breaking them down or damaging their ability to function correctly. Figure 1 indicates that after completing multiple strength tests the hernia mesh exhibited minimal changes to its overall strength properties. In each trial, the test brings the mesh to failure but showed in some cases to be slightly more resistant to breaking. Overall, the textile exhibited no significant change in strength. In summary, the results showed no change in ASTM strength properties. However, the mechanical properties observed by Kawabata testing showed significant changes. Future work could examine the potential linkage between the changes observed in the mechanical properties and any perceived changes in comfort level the patient might experience during the presence of a peptic ulcer. A longer exposure time (14 days) could be used to determine if more significant changes in properties would be observed. At the moment, poly-glycolic acid is being substituted for the common polypropylene hernia mesh to absorb other contaminates in the body. 5 Textiles that are considered absorbable surgical devices could be examined to compare the results obtained from a non-absorbable mesh. 1 "Peptic Ulcer." Mayo Foundation for Medical Education and Research (MFMER) (2011). Web. 2 Malfertheiner, Peter, Francis K L Chan, and Kenneth E L McCall. Peptic Ulcer Disease. Wiley Online Resources. Department of Gastroenterology, Hepatology and Infectious Diseases, 14 Aug Web. 3 Tamplin, Mark L. "Inactivation of Escherichia Coli O157:H7 in Simulated Human Gastric Fluid." Applied and Environmental Microbiology 71.1 (2005): Web. 4 Koeppen, Bruce M., and Bruce A. Stanton. "The Gastric Phase of the Integrated Response to a Meal." Berne & Levy's Physiology. 6th ed. New York: Mosby, Print. 5 Craig, PH, JA Williams, KW Davis, AD Magoun, AJ Levy, S. Bogdansky, and JP Jones. "A Biologic Comparison of Polyglactin 910 and Polyglycolic Acid Synthetic Absorbable Sutures." Europe PubMed Central (1975): Web. The authors wish to acknowledge the support of Philadelphia University and the PURC facility, Janet Brady, Herbert Barndt, Niny Rao, and Jeffrey Ashley. Material: Monofilament polypropylene, 66 denier, 48.5g/m 2 warp knit (See Figure 3) with the a 28 gauge structure: Guide Bar 1: 1-0/1-2/2-1/2-3/2-1/1-2, threading: 1in, 1out Guide Bar 2: 2-3/2-1/1-2/1-0/1-2/2-1, threading: 1in, 1 out Figure 1 Strength Properties of the Unexposed and Exposed Hernia Mesh Figure 3 SEM Images of Unexposed (left) and Exposed (right) Hernia Mesh Focusing on those mechanical properties that exhibited the most significant change (i.e. greater than ten percent) the following was observed: A greater change in tensile properties was observed in the wale direction of particular note is the 32% decrease in tensile resilience coupled with an increase of 14.8% in extension under maximum load. The change in these two properties would indicate greater extension coupled with lower recovery. There is no visible evidence of deterioration. The difference in appearance in Figure 3 is related to the difference in specimen preparation for SEM. Several health sciences, medical and pharmacological journals assess the effects of regular or excessive oral dosages of ibuprofen, naproxen, aspirin or other non-steroidal anti-inflammatory drugs as the leading cause for chemically induced peptic ulcers. 1 A peptic ulcer is a defect in the lining of the stomach or the first part of the small intestine. If this protective lining stops working correctly and the lining breaks down, it results in inflammation (gastritis) or an ulcer. A hole that goes all the way through the stomach or duodenum is called a perforation causing a medical emergency. Non-absorbable mesh will remain in the body indefinitely and is considered a permanent implant. It is used to provide permanent reinforcement to the repaired hernia. Any factors that alter this permanent structure present a possible health problem or comfort issue. Often treatment periods after a peptic ulcer is diagnosed, depending on the severity of the perforation, will be between 7 to 14 days. 2 Accordingly, the duration of a peptic ulcer will dictate the quantity of gastric fluids capable of emptying from the stomach into the body. Bending Compression Surface Shear Tensile This solution was prepared by dissolving the following compounds into 1.8L of deionised/distilled water at room temperature with aggregation: 6.3g D-glucose (Sigma-Aldrich/USA), 3.69g NaCl (Fisher-Science Education/USA), 1.08g KH 2 PO 4 (Sigma/USA), 0.198g CaCl 2 (Sigma- Aldrich/Mexico), 0.666g KCl (Sigma/USA), g Porcine salts (Fluka Analytical/New Zealand), and g Glycine (Sigma/Switzerland). *It should be noted that enzymes were not used because enzymatic treatments are substrate specific and gastric enzymes do not typically contain species capable of breakdown breaking down polyesters polypropylene and other plastics. A hernia occurs when an organ, intestine or fatty tissue squeezes through a hole or a weak spot in the surrounding muscle or connective tissue. Hernias often occur at the abdominal wall and are corrected using an implanted surgical device (typically a synthetically constructed knit structure) to provide additional support to weakened tissue. The synthetic materials used can be absorbable, non- absorbable or a combination of the two. Solution: Simulated gastric fluid (bottom) was generated for this experiment based on the methodology found in the Applied and Environmental Microbiology journal article by researcher Mark L. Tamplin. 3 After extensive research this solution was the most viable option due to its more accurate representation of the constituents (right) present in the human stomach as per Berne and Levy’s Gastric Phase text in Physiology, 6 th ed. 4 Gastric Phase and Constituents Figure 2 Kawabata Testing: Mechanical Properties of Unexposed and Exposed Hernia Mesh Shear hysteresis (2HG) improved by 22.39% in the wale direction and 14.76% in the course direction. The exposed product exhibited reduced bending (B) resistance in both the wale (15.29%) and course (20.97%) direction, indicating greater ease of movement. The hernia mesh exhibited a 17.29% reduction in Linearity of Compression (LC) value, indicating a greater compliance to pressure. A 13.38% improvement in Recovery from Compression (RC) was also observed. Surface friction (MIU) increased in both the wale (11.27%) and course direction (18.6%). Also noted, a 34.15% increase in the mean deviation of surface friction (MMD), (an increase in MMD properties has been identified with a feeling of roughness). SMD (surface roughness) in this case are measuring the surface contour of the warp knit structure. It is noted the the SMD values increased by 35.77% in the course direction and decreased by 14% in the wale direction. Fabric Strength: ASTM-D2261: Tearing Strength of Fabrics by Tongue Procedure; ASTM-D6797: Burst Strength Constant Rate of Extension Method; ASTM-D5034: Breaking Strength and Elongation of Textile Fabrics (Grab Test). After the solution was thoroughly mixed, 4mL of 37% 12M HCl (Sigma- Aldrich/USA) was added until the pH meter determined the solution to be The temperature controlled oven was set to 37˚C (98.6˚F).The cut textile samples were submerged (right) completely into the solution and the beaker was sealed off using parafilm and placed into the oven for seven days. Test Procedures: ASTM-D3776: Mass per Unit Area Mechanical properties evaluated under low deformation loads: Kawabata Evaluation System Testing: Tensile, Shear, Bending, Compression, Surface


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