Presentation on theme: "Redesign of a Safety Syringe University of Pittsburgh Senior Design – BioE 1160/1161 Jessica Chechak Jason Keiser Ellsworth Weatherby April 18, 2005."— Presentation transcript:
Redesign of a Safety Syringe University of Pittsburgh Senior Design – BioE 1160/1161 Jessica Chechak Jason 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 NeedleRetractable Needle 2.Sliding SheathSliding 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 use Will allow the operator's hands to remain behind the needle at all times Be an integral component of the device, and not an accessory Provide protection before, during and after use and after disposal Be 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 Use Ready To Inject Ready For Disposal After Use
Design Review Syringe 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.comquickparts.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 Use Ready To Inject Ready For Disposal After Use
Comparison to Current Syringes: Before and After Use Before UseAfter Use Our Hybrid Safety Syringe Protective Shield Safety Syringe Retractable Needle Safety 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 Considerations Cost 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)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
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 Feature A 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
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