Design of a Malignant Hyperthermia Susceptibility Screening Device Sara Doll Lisa Kaczmarski Philip Magcalas Department of Anesthesiology Children

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Design of a Malignant Hyperthermia Susceptibility
Screening DeviceSara DollLisa
KaczmarskiPhilip MagcalasDepartment of
AnesthesiologyChildrens Hospital of Pittsburgh
University of Pittsburgh Senior Design BioE1161
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Overview-The Problem

• Malignant Hyperthermia (MH) is a chain reaction
  event wherein susceptible patients, when
  administered common gas anesthetics, undergo
  drastic physiological changes.
• greatly increased body metabolism
• muscle rigidity
• fever up to or beyond 43C
• There are currently no standard devices or
  procedures in common practice to screen the
  general population for this condition.

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Overview-The Solution

• It is hypothesized that MH susceptible muscle,
  when compared to normal muscle, will be
  significantly different in compound muscle action
  potential (CMAP) and force of contraction.
• The solution lies in the design of a device that
  restricts arm movement, while measuring the
  isometric force produced by the thumb when the
  ulnar nerve is stimulated. This may then be used
  to develop a standardized protocol for MHS
  screening.
• Such a device would ultimately be beneficial to
• Anesthesiologists
• Patients and their families
• The general Population

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Project Goals

• 1. Create a device that meets design requirements

• comfortably accommodates 3 to 5-year-old patients

• securely restrains the patients forearm and hand

• fastens securely to bed in operating room

• can be easily sanitized

• can be transported with ease (lightweight)

• has minimal assembly or adjustment requirements

• can be used with both the right and left hands

• maintains the arm at the same height as the OR bed

2. Test and assess the effectiveness of the final
device in measuring forces within a specific
range
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Device Features
1- Arm board
3 Force Transducer Mount
2- Arm/hand restraints
4 - Support
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Design Options

• Force Transducer Mount
• Track
• Integrate into board
• Attach on edge
• Orientation
• Left hand only
• Ambidextrous
• Range of motion
• Fixed
• Planar
• Angular
• Support
• Moveable cart
• Vises on side of OR bed
• Integrate into existing equipment
• Elevator
• Recess for armboard

• Materials
• Board
• Wood
• Metal
• Polymer
• Straps
• Fabrics
• Polymers
• Arm/Hand Restraints
• U-shaped cushions
• Adjustable straps
• Top restraint

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The Design Process

• Prototypes (3 total)
• - Frequent meetings
• continuous design feedback and refinement of
  design requirements from mentors
• Anthropometric data
• Material samples
• arm board and straps
• The process of manufacturing
• Carrying out reality from concept - importance of
  details, details, details

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The Evolution of Design
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The Evolution of Design (contd)
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The Evolution of Design (contd)
Prototype 3
Mar.
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The Final Design
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The Final Design (contd)
TOP
BOTTOM
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Benefits of our Design
Arm board ambidextrous sized for wide
range arm/hand sizes simple construction
Force Transducer Mount translation in two
planes interchangeable (support 2 diff.
FT) ambidextrous
Support integrates with existing equipment
sturdy separable from arm board
Arm restraints adjustable removable
flexible single material, single piece
sanitizable strong (resistance to
tear)
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Benefits of our Design
Overall - Simplicity in design in
assembly in manufacture - Satisfies ALL
design requirements
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Competitive Analysis

• Competitors
• Halothane caffeine contracture testing (muscle
  biopsy segments)
• Our Strengths
• Non-invasive
• Not necessary to wait for laboratory results
• Less expensive
• Quick procedure, which may be performed pre-op
• Our Weaknesses
• Potentially less accurate
• Not testing on actual muscle fiber
• Not standardized process
• Our devices strengths outweigh the weaknesses
• However
• - Contingent upon accuracy of device
• - Reliant upon efficiency of data acquisition
  program, which lies outside the scope of this
  project

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Other Considerations for Design

• Manufacturability
• Acrylic
• Workable
• Cost
• Durable
• SolidWorks
• Ease of Use
• Available
• Experience

• Human factors
• Contextual Inquiry
• Device Observation
• Design Plan Assessment
• Heuristic Evaluation

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Regulatory Concerns

• Class II (moderate risk)
• isokinetic testing and evaluation system
  (890.1925)
• contact with skin but non-invasive
• No Predicate Device
• Currently ? 510(k) and PMA exempt
• Investigational device - clinical evaluation
  required for further development
• IDE regulation will be required
• However in the future, should the decision be
  made to pursue marketing this device, this will
  require a Class II PMA device application

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Constraints to Further Development

• Regulatory
• Again, no predicate device. Final FDA approval
  will be complicated
• Market
• Limited now to Childrens Hospital until a more
  precise MH susceptible screening protocol can be
  established.
• Economic Resources
• Limited breadth of project funds
• Human Resources
• Time constraints of all involved

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Project Management

• Our Goals

• What we Actually Achieved

• Build a device that
• Comfortably accommodates 3 to 5 year old patients
• Ambidextrous
• Fastens securely to OR bed
• Can be easily sanitized and transported with
  little assembly
• Allows for accurate measurement of contraction
  force and clear data interpretation

Test and assess the effectiveness of the final
device in measuring forces within a specific range

• Force Transducer Calibration
• Known force range
• Located an amplifier
• Preliminary signal processing
• Waveform filtering
• Establish force-voltage relationship

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Project management (contd)
Projected Schedule
Completed Schedule

• December
• - Discussed device requirements with advisors
• - Researched materials

• December
• - Preliminary SolidWorks drawing for armboard,
  support
• - Order force transducer (Grass model FT03)
• January
• - Gather materials for prototype
• - Build initial prototype
• February
• - Prototype testing
• - Design revisions
• - Finalize SolidWorks drawing
• - Order final materials
• March
• - Build/Assemble device
• April
• - Device testing, as time allows
• - Draft final report and presentation

January - Gathered materials for and built
Prototype 1 - Ordered force transducers
(Grass FT03, FT10) - Prototype 1 assessment
February - Design revisions -
Gathered materials for and built Prototype 2
- Prototype 2 Assessment - Preliminary
SolidWorks drawing
March - Ordered final materials -
Anthropometric research - Gathered
materials for and built Prototype 3 -
Finalized dimensions and SolidWorks Drawings
- Submitted design to machining
April - Device machining underway -
Draft final report and presentation
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Project management (contd)

• Who was responsible what

• Lisa Kaczmarski
• Material Research
• Materials Acquisition
• Contact with Suppliers
• Prototype 1
• Final Product (straps and armboard)

• Philip Magcalas
• Device Concept Drawings
• Anthropometric Research
• Force Transducer Mount Solid Works
• Prototype 2
• Final Product (FT supports)

• Sara Doll
• Armboard SolidWorks
• Strap SolidWorks
• Concept SolidWorks
• Mentor Meetings
• Prototype 3

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Acknowledgements

• Dr. Brandoms Clinical Research Fund
• Childrens Hospital of Pittsburgh
• Dr. Barbara Brandom
• Dr. Robert Sclabassi
• Dr. Andreas Hoyer
• Prof. Mark Gartner
• Dr. Mingui Sun
• Joe Beuten
• Total Plastics, Inc.
• George Kurzdorfer
• University of Pittsburgh
• Department of BioEngineering

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Thank you!Questions?
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Design Details Arm Board
H30cm W33cm
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Design Details - Support
H9.8cm W17.5cm
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Design Details Force Trans. Mount
H4.4cm W10.2cm
H7.3cm W28.1cm
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Design Details - Straps
large
small
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