This is our final spinal tap presentaiton for our senior design project.
Text of Final Presentation Final Draft
1. William H. Wilson IVBiomedical Engineering Emily HeebBiomedical Engineering William BowlusBiomedical Engineering Andy Jetter Biomedical EngineeringStephen Nelson Industrial Design Crystal BarronNursing
2. Design a cerebrospinal fluid collecting device to be used in under resourced environments by personnel with minimal training Current difficulties of procedure: Finding insertion location Determining insertion depth 3. 18g Introducer Needle Provides a stable path towards the spinal column, but stops short of dura. 4. Flange Grips Ergonomic design provides stability and control during insertion. 5. Stylet Prevents coring when inserting the introducer. Twist removable cap. 6. Funneled Lead-in Assists user when inserting whitacre needle into the introducer. 7. 22g Whitacre Needle Provides access to dura while causing minimal trauma. Reduces post- puncture headache. 8. Dual Needle Approach Whitacre needle advances through the introducer needle 9. Advancement Knob Rotation allows for a gradual insertion rate of the whitacre needle 10. Threaded Region 4mm pitch needle advancement 11. Luer-lock Allows for connection of a monometer to measure CSF pressure. 12. Insertion Window Locates the L4-L5 intervertebral space 13. Alignment: Iliac Crest Aligns to the iliac crests, which identifies the L4-L5 intervertebral space 14. Alignment: Spine Aligns to the midline of the spinal column 15. Adhesive Allows for fixation to the patient 16. Accommodates three different hand positions13 2 17. Usability Testing Cadaver Labs Tissue Coring Test User Drape Studies Fluid Flow Analysis Device Failure analysis Mechanical Failure AFMEA 18. Cadaver Lab Test overall usability of device Cadaver tissue too rigid for assessment of functionality Tissue Coring Test Investigated if a whitacre (bullet tip) needle will core tissue as it is advanced into the spinal column Tests performed on porcine tissue The whitacre needle did not core tissue while being advanced 19. Assess fluid flow through various needles Determine time to visual CSF flow. Results 18 Gage Quinke - 1 mL / 14 sec 22 Gage Quinke - 1 mL / 2.0 minutes 25 Gage Whitacre - 1 mL / 7.9 minutes CSF fluid in flash chamber - < 1 sec 20. To assess the drapes ability to properly locate the L4-L5 vertebral space Study performed by untrained users Nursing and Biomedical Engineering Students Results Round 1 First Generation Drape Average X deviation 1.10 cm Average Y deviation 4.84 cm Drape did not meet horizontal or vertical accuracy specification 21. Results Round 2 Second Generation Drape Average X deviation 0.80 cm Average Y deviation 1.42 cm Better accuracy when applied to patient lying down Drape met horizontal accuracy specification More work needed on vertical accuracy 22. Application Failure Modes and Effects Analysis (aFMEA) High Risk of Bumping the System while inserted in patient Possible design control: Adhesive securing disc Sufficient thread lubrication is imperative Likelihood of user impatience while unscrewing the dial Possible design control: Quick release feature Likelihood of sterility compromise Possible design control: Training supplement, significantemphasis in IFU 23. Whitacre Needle Buckling Critical Buckling Force = 5 lbf Insertion Force = 2.25 lbf Introducer most susceptible: Flange Bending Break Threaded Shaft Bending Break Threaded Shaft Torsion Break 24. Flange Bending Break Utilized simple model to replicate a worse scenario Stress 700 psi Threaded Shaft Bending Break Force applied at tip of shaft = 4 lbf Stress 2,700 psi Threaded Shaft Torsion Break For Torque = 15 lbf in Shear Stress 2,250 psi Material Yield Stress 3,000 psi 25. Material Yield Stress 3,000 psi Minimized cost High importance for device success in target demographic Injection Molding compatible Durable 26. Two types of polypropylene are top choices Polypropylene (50% Glass Fiber Filler) Better Mechanical Properties More Expensive Opaque Polypropylene (Copolymer, UV Stabilized) Translucent Cheaper Acceptable Mechanical Properties 27. Polypropylene (copolymer, UV stabilized) Yield strength 3,670 psi Bulk cost $1.00/lb UV Radiation Durability: Good Next Steps Additional tests to verify mechanical stability Investigate costs involved with manufacturing processing Injection Molds, etc. Sterilization investigation 28. Finalization of needle design Investigating Additional features Quick Release of threads Relative rotation for knob Securing disc to skin Revision of drape Still need to meet vertical accuracy requirement Refinement of application procedure Layout of alignment features 29. Verification and Validation Clinical Efficacy Porcine model Clinical trials Production Trials Testing on manufactured prototypes Durability testing: aging, drop testing, etc.