This is our final spinal tap presentaiton for our senior design project.

1. William H. Wilson IV Biomedical Engineering
Emily Heeb Biomedical Engineering
William Bowlus Biomedical Engineering
Andy Jetter Biomedical Engineering
Stephen Nelson Industrial Design
Crystal Barron Nursing

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

5. 18g Introducer Needle
Provides a stable path towards the
spinal column, but stops short of dura.

6. Flange Grips
Ergonomic design provides stability and
control during insertion.

7. Stylet
Prevents coring when inserting the
introducer. Twist removable cap.

8. Funneled Lead-in
Assists user when inserting whitacre
needle into the introducer.

9. 22g Whitacre Needle
Provides access to dura while causing
minimal trauma. Reduces post-
puncture headache.

10. Dual Needle Approach
Whitacre needle advances through
the introducer needle

11. Advancement Knob
Rotation allows for a gradual
insertion rate of the whitacre needle

12. Threaded Region
4mm pitch needle advancement

13. Luer-lock
Allows for connection of a monometer
to measure CSF pressure.

15. Insertion Window
Locates the L4-L5 intervertebral space

16. Alignment: Iliac Crest
Aligns to the iliac crests, which
identifies the L4-L5 intervertebral space

17. Alignment: Spine
Aligns to the midline of the spinal
column

18. Adhesive
Allows for fixation to the patient

22.  Accommodates three different hand positions
1 3
2

26.  Usability Testing
◦ Cadaver Labs
◦ Tissue Coring Test
◦ User Drape Studies
 Fluid Flow Analysis
 Device Failure analysis
◦ Mechanical Failure
◦ AFMEA

27.  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

28.  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

29.  To assess the drape’s 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

30.  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

31.  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, significant
emphasis in IFU

32.  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

33.  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

34.  Material Yield Stress ≥ 3,000 psi
 Minimized cost
◦ High importance for device success in target demographic
 Injection Molding compatible
 Durable

35.  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

36.  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

37.  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

38.  Verification and Validation
◦ Clinical Efficacy
 Porcine model
 Clinical trials
◦ Production Trials
 Testing on manufactured prototypes
◦ Durability testing: aging, drop testing, etc.