Fibrinogen Monitor Project Team Members: Albert Nguyen & Juan - - PDF document

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Fibrinogen Monitor Project

Team Members: Albert Nguyen & Juan Vizcarra Project Mentor: Dr. Nathan White

Background

• Trauma: sudden and severe injury that requires immediate medical attention
• Leading cause of death for the young population in the world
• Primary culprit: uncontrolled bleeding
• Trauma-Induced Coagulopathy (TIC): Impaired ability to form a healthy

blood clot due to heavy blood loss from trauma

• 4-fold increase in mortality when present

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Background

• Current treatments?
• administration of resuscitation fluids
• Short timeframe for intervention
• 50% of civilians hemorrhaging die

before reaching hospital

• 85% of military hemorrhaging die

before reaching surgery

Consequences of Misdiagnosis

Background

Coagulopathy?

No Yes

• Standard

rescucitation fluids given

• Patient bleeds to

death

• Coagulants

given

• Thrombosis or

stroke

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Background/Clinical Need?

• Role of Fibrinogen
• releases fibrin monomers which leads to scaffold of clot
• depletes first during trauma
• shown to be strong indicator of coagulopathy
• Current Limitations
• Devices that too big, slow, and thus inaccessible for urgent trauma patients
• Need
• A point-of-care device that can access the quality of a clot quickly, reliably, and

in a portable manner

Previous Capstone Designs

• Measurements:
• Stiffness of clot
• Turbidity
• Ratio of two measurements correlated

with fibrinogen concentration

• Limitations:
• Good PPP results, bad whole blood

results

• Correlation was not accurate enough

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Design Specifications

• Aim: Design device to monitor clot structure and strength to determine

whether patient has coagulopathy

• Important Characteristics of Device
• Quick response time
• Portable
• Reliable
• Sturdy

Proposed Design

Design Overview

• Bifurcation of sample into two

chambers

• Porosity test through a microfluidic

channel

• Mechaial strength test through a

cantilever approach

• Measurements give rise to new

hemostatic ratio

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Porosity Test

• Permeability/Porosity calculated

based on Darcy’s Law

• Calcuated after certain amount of

buffer flows through or certain pressure drop

• Fluid pump/sensor to regulate and

measure pressure

: = − − μ

Mechanical Strength Test

• Idea based on AFM technology
• Motion driven by solenoid
• Custom designed silicone

cantilevers for increased sensitivity

• Segmented photodiode for detection
• Force-displacement measurements

to approximate tensile modulus

D = ∗ ∆ = ∗

A B C D Δ =

−

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Materials

• solenoid
• linear variable differential transformer
• segmented photodiode
• laser light
• collimator lenses
• silicone rubber sheets
• aluminum coating
• 3D Printer – PDMS material
• PBS buffer
• rubber tubing
• glass pipets
• pressure pump/sensor
• porcine blood

Resources:

• UW fabrication facility
• TEG & ROTEM (Harborview)

Challenges

• Cantilever technology concerns: sensitivity
• small size cantilevers are sensitive to thermal changes and small vibrations
• initial loading might be damaging to cantilever
• Device concern: connections of both technologies
• Prorosity concerns: few past studies on desired scale and sample size
• Time constraints
• Building from the ground up, designing might be as far as we go

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Present Tasks

• Recreate the porosity results from published work
• smaller scale and shorter time frame
• Building of cantilever set-up
• designing the custom cantilevers
• ptimizing the size and arrangement of set-up
• sensitivity testing to show its improvement from previous work
• Porcine blood sample testing
• Pig’s blood will be supplied by Dr. White’s Laboratory in Harborview

Deliverables

• Phase 1:
• Prototype of device incorporating fluid channel and cantilever approach
• Resolution data: ΔVoltage/Δ[Fibrinogen]
• Noise-effective control of mechanical strength test
• Porosity measurements under 10 minutes
• Phase 2:
• Portable device that contains our two test mechanisms
• Injected sample able to disperse into two test chambers
• User friendly control and readout
• Quick response time: 1-5 minutes

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Criteria for Success

• At least 10-fold increase in sensitivity of mechanical strength test
• Increased correlation of blood loss/[fibrinogen]

and the new ratio

• Testing methods effectively employed in the

millimeter scale

• Works effectively with whole blood samples

Thank you! Questions?