Redesign of a Safety Syringe University of Pittsburgh Senior Design – BioE 1160/1161 Jessica...
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Transcript of Redesign of a Safety Syringe University of Pittsburgh Senior Design – BioE 1160/1161 Jessica...
Redesign of a Safety Syringe
University of PittsburghSenior Design – BioE 1160/1161
Jessica ChechakJason Keiser
Ellsworth Weatherby
April 18, 2005
Presentation Overview
• Problem Statement• Proposed Solution
• Specific Aims• Design Considerations• Design Requirements
• Design Process• Initial Design• Final Design• Design Review • Prototype Fabrication• Functionality Testing
• Quality Systems• Manufacturability• Human Factors• Regulatory
• Economic Considerations
• Project Timeline• Group Responsibilities
• Ellsworth• Jason• Jessica
Problem Statement•There are approximately 236,000 percutaneous injuries resulting from accidental needlesticks every year
•50% of injuries occur between the time the procedure is completed and disposal of the device•20% are associated with disposal of the device
•Needlestick injuries expose health care workers to diseases caused by bloodborne pathogens
•AIDS (from HIV)•0.001 probability of contracting per needlestick
•hepatitis B (from HBV)•0.126 probability of contracting per needlestick
•hepatitis C (from HCV)•0.024 probability of contracting per needlestick
•Adoption of needles with safety features would prevent about 69,000 needlesticks each year
Proposed Solution
We propose the creation of a single use safety syringe that includes several categories of safer device features:
1.Retractable Needle
2.Sliding Sheath
3.Screw-on cap
• This novel design combines several safety features to satisfy FDA guidelines
• These engineering controls effectively reduce the risk of an exposure incident in several sites
Specific Aims
• Modify current “safety syringe” designs to increase safety to the user as well as anyone who is exposed to the syringe. • Our proposed design contains aspects of several
marketed designs, along with a few new features• Current models may have an exposed needle or a
retractable needle that can leak – both are biohazards. • The combination of a retractable needle, needle shield
and screw on cap will prevent needle-stick injury and leaking of biohazardous materials before and after use.
• The combination of safety features will ease disposal and prevent reuse.
Specific Aims
• Fabricate a sufficient number of prototypes to support Phase I functionality testing.• The design was drafted in SolidWorks • The body of the syringe was produced with a rapid-
prototyper thorough the process of Stereolithography (SLA).
• The parts were hand-assembled by the Design Coordinator using a documented process.
• Several variations of the design were prototyped to assure best fit, and to experiment with various materials
Specific Aims
• Test the Phase I prototypes, in vitro, to demonstrate basic functionality.• The research team used an in vitro testing
apparatus to test the syringes. • Tests will show that the prototype successfully
meets the functionality standards set forth by the team: • no leakage pre-use or post use• successful fluid delivery• a retractable needle
• FDA Guidelines• 29 CFR part 1910.1030, The Bloodborne Pathogens
Standard• Enforced by OSHA through citations and fines
• Injuries Statistics• 236,000 needlesticks/year• Every year about 1.3 million people die of blood infections caused
by the re-use of syringes
• Consequences of needlesticks• Disease transmission• Post-exposure prophylaxis ~ $500-$1,000 per injury• 1.7 million workers needed time off to recuperate after
incidents
Initial Design Considerations
Safety Syringe Design Requirements
Our design goals were to achieve every FDA recommended design feature characteristic of a safer device:
Provide a barrier between the operator's hands and the needle after useWill allow the operator's hands to remain behind the needle at all timesBe an integral component of the device, and not an accessoryProvide protection before, during and after use and after disposalBe simple and self-evident to all operators and require little training and no particular expertise
Design Process: Initial Design
• The initial design utilized a push button to retract the protective shield. • This facet was redesigned to
reduce the complexity of the design and to reduce the cost of mass manufacturing.
• The retractable needle mechanism was initially activated when the plunger reached the bottom of the syringe body.• This was modified to make the
retractable needle mechanism user activated.
• Initially the syringe was intended to be pre-filled; this modification allowed the syringe to be sold unfilled.
Design Mid-December
Design Process: Final Design
• The protective shield was designed to allow the user to slide it up and down the syringe body without having to compress a button, thus simplifying the device.
• The retractable needle is activated by a spring loaded mechanism located in the luer of the needle. • This system is triggered by a 5lb
downward force on the plunger by the user after the medication has been delivered.
• The protective cap remains locked into position before and after use until a force of 1lb is applied.
Final Design: Before Use
Final Design: Intended Use
Before UseReady To
Inject
Ready ForDisposalAfter Use
Design ReviewSyringe Body
Are the dimensions in mm? Yes
Does the body fit into the protective shield? Yes
Does the syringe body have a 9mm opening for the plunger?
Yes
Does the syringe body bottom opening have a luer thread pattern comforming with ISO 594-1:1986 "Female Fittings"?
Yes
Does the body have an opening to lock-in the push button mechanism?
Yes
Protective Shield
Are the dimensions in mm? Yes
Does the protective shield fit over the syringe body?
Yes
Does the shield have a luer thread pattern on the ouside end conforming to ISO 594-2:1998 "Male Fittings"?
Yes
Does the shield have a square pattern on the top for use with the push button?
Yes
Does the luer threading and shield fit into the Protective Cap?
Yes
Protective Cap
Are the dimensions in mm? Yes
Does the Cap have a luer thread pattern on the inside conforming to ISO 594-1:1986 "Female Fittings?“
Yes
Does the luer threading and cap fit onto the protective shield?
Yes
Backing Pad
Are the dimensions in mm? Yes
Does the backing pad fit against the back of the protective shield?
Yes
After all questions were answered “Yes” prototyping began.
Prototype Fabrication
• The prototype was produced by quickparts.com• Solidworks files of the design were used • Stereolithography (SLA) rapid prototyping was used
to produce the parts• The initial prototypes were made of Somos® 14120 (a
low viscosity photopolymer – white color)• Issues with tolerances and angle of threads
• A second set of prototypes was made also using Somos® 14120
• Parts were assembled, fit was good, but thread angle needed to be changed
• A final set of prototypes was made of Somos® 11120 (a low viscosity photopolymer – clear color)
• New material had different tolerances, but we were able to combine parts to produce the final prototypes
Prototype: Intended Use
Before UseReady To Inject
Ready For DisposalAfter Use
Comparison to Current Syringes:Before and After Use
Before Use After Use
Our HybridSafety Syringe
Protective ShieldSafety Syringe
Retractable NeedleSafety Syringe
Normal Syringe(Non-Safety)
Functionality Testing
• Functionality testing was performed to demonstrate that the syringe met the standards for success:
• No leakage pre-use or post use• Successful fluid delivery• A retractable needle• Operational needle shield• Operational screw-on cap
Quality Systems Considerations
Manufacturability• Simple Design
• Needle is surgical grade stainless steel (standard size 23 gauge)
• Plastic components will be made from PTFE and polypropylene
• Rapid Injection Molding will be used for production of plastic components
Human factors• Ease of use• Biocompatability of components• Non-Allergenic components• Easily disposable – Biohazard safe
Regulatory• 29 CFR 1910.1830 - Bloodborne Pathogen
standard• The Occupational Safety and Health
Administration (OSHA) promulgates a standard to reduce occupational exposure to bloodborne pathogens through a combination of:
• Engineering controls• Work practice controls
• Enforcement Procedures • Show evidence of adoption of devices/engineering
controls that reduce exposure • Document plan annually and any difficulties • Inspections: complaints & some scheduled inspections • OSHA does not require a specific device
Quality Systems Considerations
• Regulatory (cont.)• The Needlestick Safety and Prevention Act
• Directed OSHA to revise the bloodborne pathogen standard:
• New definitions in engineering controls • Sharps with engineering sharps injury protection• Needless systems
• Annual review/update of exposure control plan• Employers are required to select safer needle devices as
they become available• Involve frontline workers in device selection
• maintain detailed sharps injury log
• The Centers for Disease Control and Prevention estimated in March 2000 that selecting safer medical devices could prevent from 62 to 88 percent of sharps injuries in hospital settings.
Quality Systems Considerations
Economic ConsiderationsCost of Safety devices:
• 1 to 3.5 times more than conventional devices• The increased purchase costs of using needles with safety
features would be between $70 million and $352 million per year.
Cost of Post-Exposure Prophylaxis: • $500 low; $1,500 moderate; $2,500 high risk • Eliminating 69,000 needlesticks per year would reduce post-
exposure treatment costs for by between $37million and $173 million per year.
Market size• 550M per year (US hospital patients)
Frost & Sullivan (www.chetday.com/medmistakes.html)
Distribution• Hospitals, Individuals
Cost Effectiveness of Safety Devices
Cost of safety devices are offset by cost of post-exposure prophylaxis and follow up in medium
and high-risk scenarios
Projected Project Timeline
This is our initial project timeline.
We remained on schedule within a day or two of our initial project deadlines. We received our initial
prototype earlier than expected. This gave us time for several redesigns to produce the final prototype.
Group Responsibilities
• Ellsworth: Business Manager / Safety Coordinator
• Jason: Design Coordinator
• Jessica: Project Coordinator
Ellsworth’s Achievements
• Business Manager• Research on Market Size… etc.• Creation of final PowerPoint presentation• Updating controlled documents
• Safety Coordinator• Research on OSHA standards for “Safe
Sharps”
• Writing Section B of the SBIR Phase I Application
• Design Coordinator:• Modeling of design in Solidworks• Design modifications• Design Review• Prototyping• Functionality Testing• Writing Section D of the SBIR Phase I
Application
Jason’s Achievements
• Project Coordinator• Scheduling Team meetings• Creation of final PowerPoint presentation• Writing Sections A and C of the SBIR Phase I
Application• A: Specific Aims• C: Relevant Experience / Preliminary Work / Design
Review
• Editing the SBIR Phase I Application• Updating Controlled Documents
Jessica’s Achievements
Any Questions?
Hypodermic syringes with “Needle-Sheath” safety feature
• Active Safety Feature
A feature that requires the operator to activate the safety mechanism, and failure to do so leaves the operator unprotected “Needle-sheath” syringe
Hypodermic syringes with “Retractable Technology” safety feature
• Passive Safety FeatureA safety feature that remains in effect before, during and after use, the operator does not need to "activate" the safety feature
• Integrated Safety Design
The device has the safety feature included into its design and it can not be removed or inactivated. This is the preferred safety feature.
Retractable needle safety syringe