Design of a Malignant Hyperthermia Susceptibility Screening Device Sara Doll Lisa Kaczmarski Philip Magcalas Department of Anesthesiology Children’s Hospital of Pittsburgh University of Pittsburgh Senior Design – BioE1161

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 43°C There are currently no standard devices or procedures in common practice to screen the general population for this condition.

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

Project Goals 1. Create a device that meets design requirements 2.Test and assess the effectiveness of the final device in measuring forces within a specific range 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 fastens securely to bed in operating room securely restrains the patient’s forearm and hand comfortably accommodates 3 to 5-year-old patients

Device Features 1- Arm board 2- Arm/hand restraints 3 – Force Transducer Mount 4 - Support

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

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

The Evolution of Design Dec. ConceptPrototype #1 Jan.

The Evolution of Design (cont’d) metal Nylon Velcro straps rigid, 1-1/2” polymer Flexible polymer Jan. Concept #2 Feb. Prototype #2

The Evolution of Design (cont’d) Prototype #3 Mar.

The Final Design 3 – Force Transducer Mount 2- Arm/hand restraints x Support x 3 1- Arm board

The Final Design (cont’d) TOPBOTTOM

Benefits of our Design Arm board ambidextrous sized for wide range arm/hand sizes simple construction Arm restraints adjustable removable flexible single material, single piece sanitizable strong (resistance to tear) Force Transducer Mount translation in two planes interchangeable (support 2 diff. FT) ambidextrous Support integrates with existing equipment sturdy separable from arm board

Benefits of our Design Overall - Simplicity in design in assembly in manufacture - Satisfies ALL design requirements

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 device’s 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

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

Class II (moderate risk) ‘isokinetic testing and evaluation system’ ( ) 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 Regulatory Concerns

Constraints to Further Development Regulatory Again, no predicate device. Final FDA approval will be complicated Market Limited now to Children’s 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

Project Management Our GoalsWhat we Actually Achieved 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 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 Arm Board and Support Currently in machining Overall - accomplished a simple, compact design that satisfies all design requirements Straps (Adjustable size) Assembled Force transducer Grass/Astromed FT03, FT10 obtained Mounting Device Currently in machining Device In Pre-Assembly

Project management (cont’d) 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 December - Discussed device requirements with advisors - Researched materials February - Design revisions - Gathered materials for and built Prototype 2 - Prototype 2 Assessment - Preliminary SolidWorks drawing April - Device machining underway - Draft final report and presentation March - Ordered final materials - Anthropometric research - Gathered materials for and built Prototype 3 - Finalized dimensions and SolidWorks Drawings - Submitted design to machining January - Gathered materials for and built Prototype 1 - Ordered force transducers (Grass FT03, FT10) - Prototype 1 assessment Projected ScheduleCompleted Schedule

Project management (cont’d) Who was responsible what Sara Doll Armboard SolidWorks Strap SolidWorks Concept SolidWorks Mentor Meetings Prototype 3 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)

Acknowledgements Dr. Brandom’s Clinical Research Fund Children’s 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

Thank you! Questions?

Design Details – Arm Board H=30cm W=33cm

Design Details - Support H=9.8cm W=17.5cm

Design Details – Force Trans. Mount H=4.4cm W=10.2cm H=7.3cm W=28.1cm

Design Details - Straps large small