final presentation final draft

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

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

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William H. Wilson IV

Emily Heeb

William Bowlus

Andy Jetter

Stephen Nelson

Crystal Barron

Biomedical Engineering

Biomedical Engineering

Biomedical Engineering

Biomedical Engineering

Industrial Design

Nursing

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

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

Flange GripsErgonomic design provides stability and control during insertion.

StyletPrevents coring when inserting the introducer. Twist removable cap.

Funneled Lead-in

Assists user when inserting whitacre

needle into the introducer.

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

Dual Needle Approach

Whitacre needle advances through

the introducer needle

Advancement Knob

Rotation allows for a gradual

insertion rate of the whitacre needle

Threaded Region4mm pitch needle advancement

Luer-lockAllows for connection of a monometer to measure CSF pressure.

Insertion WindowLocates the L4-L5 intervertebral space

Alignment: Iliac CrestAligns to the iliac crests, which identifies the L4-L5 intervertebral space

Alignment: SpineAligns to the midline of the spinal column

AdhesiveAllows for fixation to the patient

Accommodates three different hand positions

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Usability Testing◦ Cadaver Labs

◦ Tissue Coring Test

◦ User Drape Studies

Fluid Flow Analysis

Device Failure analysis◦ Mechanical Failure

◦ AFMEA

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

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

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

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

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

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

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

Material Yield Stress ≥ 3,000 psi

Minimized cost◦ High importance for device success in target demographic

Injection Molding compatible

Durable

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

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

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

Verification and Validation

◦ Clinical Efficacy

Porcine model

Clinical trials

◦ Production Trials

Testing on manufactured prototypes

◦ Durability testing: aging, drop testing, etc.