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path of standard traceability hiearchy + standard
- ISO31/1000
- international bureau of weights & measures
- national institute of standards
- reference laboratory
- measurement device
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def'n: biomedical engineering
application of math & physics to biological and medical problems
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code of professional practice (7)
- patient/user safety
- protection of environment
- know one's own limitations
- confidentiality
- continuing education
- conflict of interest
- fairness/credit
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life cycle of medical device
- research
- development
- evaluation
- marketing
- manufacturing
- procurement
- utilization
- disposal
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why standards (4)
- a reference
- desirable attributes of a product, process, or system
- define safety, protection of environment, conflict of interest; professional practice
- legal protection
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physical standards traceability (more defined)
- national or international standards (NRC/NIST)
- 10 standard (national level)
- reference standards/transfer standards
- working standards
- client test equipment, shop/level standards, 20 standards
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instrument calibration involves:
- condition of receive & return
- date/env of calibration
- expiration
- standards/equip'ts used
- certificate of traceability
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def'n: safety & effectiveness (9)
- identify risks inherent to device, eliminate/reduce risk, provide protection against those risks, provide info related to risks that remain
- not compromise clinical safety condition
- conforms to safety principles
- performance over life time
- transport & storage requirements
- material compatible
- safe sterilization method
- software performance validation
- appropriate training manuals
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def'n: process standards + standards
- control manufacture process
- ISO9000-2003 (General QA) ~ ISO13485 (Medical QA) ~ 21CFR820 (Quality System Requirements)
- ISO14971-2000 (Risk Management)
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def'n: collateral/horizontal standards
general, many types of equipments e.g. CISPR.11
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def'n: particular/vertical standards
- device specific
- e.g. AAMI EC12-1991
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Technical Standards def'n + examples
- technical requirements & test methods
- CSA-Z32-99 (electrical safety & essential electrical system in health care facilities) e.g. backup power requirements
- IEC 60601-2: Particular requirements for safety
- IEC 60601-1: General req'ts for basic safety & essential performance
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def'n: consensus/voluntary standards
- derived by standard organizations
- not part of gov't body
- not created by treaty
- most standards
- IEC, ANSI, CISPR
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standards sources
- notified bodies:
- - CSA (Canadian Standards Assoc)
- - Underwriters Laboratory (U.S. version of CSA)
- associations:
- - AAMI (Association for the Advancement of Medical Instrumentation)
- - ANSI (American National Standards Institute)
- - ISO (International Standard Organization)
- - ECRI
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contents of standards
- scope (disclaimer, what is covered & not)
- purpose (intended or desired result)
- definitions
- requirements
- test methods (how requirements verified)
- appendixes
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Table of diff standards & jurisdictions
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standard compliance
- self certification, regulatory body right to audit
- third party certification, gives certificate
- diff jurisdiction, diff certification requirements
- CSA Certification Program: certifies process & device (>1)
- CSA Special Inspection Program: certifies 1 particular device (only 1)
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def'n: calibration control system
- ensures measurement, test, and process-control equip'ts & materials are calibrated and maintained w/in tolerance limits sufficient for individual tasks to meet regulatory & quality requirements
- ensures control of environmental conditions to get accurate results
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def'n: macroshock
high current (mA), low density, transcutaneous
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def'n: microshock
low current (uA), high density, introduced to heart
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how do electric effects cause human harm?
- P = I2R --> burns tissue
- evokes action potential
- heart fibrillation
- current threshold for macroshock
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Current perception with 60 Hz
- 1 mA: threshold of perception
- 5 mA: max harmless current
- 10-20 mA: can't let go, sustained muscular contraction
- 50 mA: pain, faint, exhaustion
- 100-300 mA: ventricular fibrillation start
- 6 A: temporary respiratory paralysis, burns, myocardial contraction
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def'n: leakage current
inherent flow of current from an energized cct to conductors
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purpose of ground wires
- drain leakage currents
- create short cct in case of fault
- min. unwanted noise
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def'n isolated power
electrical system in which no cct conductor is connected directly to ground
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advantages of isolated power
- no spark at ground fault
- SF fault to ground no shock occurs
- fault does not affect operation of device
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def'n: LIM
- line isolation monitoring system
- displays current that would flow if there's direct fault to ground to the equipotential grounding system
- impedance measuring device
- indicate degree of isolation from ground to isolated portion
- trig at ~2mA
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def'n: GFCI
- Ground Fault Circuit Interrupter
- interrupts power if Ileak >= 5 mA or when Iin >> Iout
- protection against macroshock
- not for OR use b/c power shuts down
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def'n: equipotential ground
- if long distance to panel can have voltage drop
- green-yellow wire insulation
- ensure all same length
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Gas safety (10)
- proper ID: color, label, PISS (pin index safety system), DISS (diameter index safety system)
- storage & transportation of gas containers: valve protection cap, chains
- leaks: fire hazard
- oil/grease free environment: high pressure O2 + oil/grease = burning/explosion hazard
- sparks: explosion hazard
- ventilation: accumulation of gases in enclosed areas
- relieve valve location & air intake
- cryogenic burns
- shock-waves: no 1/4 turn valves with high pressure systems
- dust contamination
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def'n: problem solving
process to find answers in engineering design, design improvement, and troubleshooting
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problem solving tools (6)
- brainstorming
- reverse engineering
- decision tree
- PMI
- SWOT
- Critical Path / Gantt
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troubleshooting tools (4)
- troubleshooting flowchart
- fault tree analysis
- half-split analysis
- identical systems analysis
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troubleshooting in BMET includes:
- clinical considerations
- documentation
- incident reporting
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Rayleigh resolution
- Rrayleigh = h {1.22 x lambda / (2 x NA) }
- distance between peaks of 2 light spreads
- point spread function, defines the design of the lens
- higher resolution have higher Rrayleigh
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steps in problem solving
- 1. problem definition: understand/verify problem
- 2. background research
- 3. high level approach: problem isolation
- 4. idea generation: possible causes
- 5. idea formulation: test & measurement methods
- 6. idea evaluation and implementation: test & measure
- 7. verification/validation: follow-up document
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def'n: design problem definition (5)
- summary of device and intended use
- general operational specifications/initial requirements
- functional specifications: performance
- non-functional specifications: safety & standard compliance
- packaging & cost
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brainstorming in problem solving
- method for developing creative solutions to problems
- encourages lateral & creative thinking
- no criticism
- choose best solution with decision making tools
- individual or group
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def'n: reverse engineering
- adopt ideas from similar systems, processes, or problems and modify to suit our needs
- consider intellectual property issues & give credit where it's due
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steps to construct a decision tree
- 1. assign value/cost to outcomes
- 2. assign probability to each branch according to effort
- 3. calculate value to next higher level
- 4. select path with highest value
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def'n: PMI
- Plus-Minus-Interesting
- plus: pros
- minus: cons
- interesting: implications & possible outcomes for taking action
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def'n: SWOT
- Strength: what it does well
- weakness: what it does less well
- opportunity: what current trends favour it ssuccess?
- threats: what obstacles exist to its success?
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Critical Path Analysis and Gantt Chart
- Planning of an activity/project
- sub-dividing problems into more manageable tasks
- resource assignment
- budgeting
- determine critical paths & tasks
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Troubleshooting Flow Chart
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Fault Tree
- typically provided by manufacturer in manual under troubleshooting section
- lists problems, provides typical possible causes and corresponding remedies
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Half Split Analysis
- start with system block diagram or flowchart
- define input & faulty output
- split diagram into half or at a convenient boundary
- continue to split until problem is isolated & part, code, or process can be replaced
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Identical System Analysis
- 2 identical systems are available & 1 works
- troubleshoot by swapping suspicious components
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Troubleshooting picture
- know the equipment: patient/user, function, env't
- resources: manual, manufacture, databases, ECP
- back to basics: common faults (age, user error, misuse, power interruption), replaceable parts, analysis
- communication: documentation (logbook, ECP)
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medical device reporting + standard
- 21CFR803
- report if caused or contributed to death or serious injury
- submit annual report, event file, incident report w/in 5, 10, and 30 days
- reporting procedures must be developed, implemented, and maintained
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policy on managing the investigation of incidents
- initial response: secure the scene, stop dmg spread, know seq of events
- gather incident info
- remedial action
- coroner's inquests: if death unexpected, will be investigated
- internal communication and documentation: report to supervisor
- external communication: FDA, Health Canada
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scope of research
- scientific/clinical investigations
- technical feasibility
- device classifications
- market assessment / requirements
- risk assessment
- knowledge of basic properties and functional requirements
- competitive analysis
- customer service plan
- regulatory and clinical strategy
- develop business case
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scope of development
- product definition
- intellectual property generation & strategy
- requirements
- high-lvl product and process design
- product design, verification and validation
- process development
- supply-chain development
- clinical studies/trials and regulatory submissions/approval
- product certification
- risk assessment & mitigation
- develop & update business plan
- commercialization strategy & marketing plans
- design transfer design
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scope of operations
- pilot production
- production
- market rollout
- distribution channel management
- maintenance and service
- continuous improvement programs
- pos-market clinical studies
- market feedback
- disposal
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rational for QSR (8)
- encourage safety & effectiveness
- encourage a systematic, structured, and documented process
- encourage customer based development
- encourage continuous improvement
- enforce risk management development & operation
- enforce planning and evidence-based development, manufacturing, and operation
- enforce definition and verification/validation of requirements
- encourage proactive organizations
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proactive vs. reactive company
- proactive: keeps changing design, start slow, but less problems in the future
- reactive: high productivity in the beginning, lots problems later
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def'n: 1-10-100 rule
- 1: cost of preventing defect before it occurs
- 10: cost of correcting a defect before it reaches the customer
- 100: cost of correcting after it reaches the customer
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Types of Device Classifications
- Regulatory: HBFB, FDA, MDD, etc
- Electrical: IEC60601, degree of protection against electrical shock, types B, BF, CF
- Electrical: IEC60601, type of protection against shock, class I (relaxed insulation), class II (enhanced insulation)
- Laser: eye safety, aversion response, wavelength and output power, class I, II, IIA, IIIa, IIIb, and IV (old); 1, 1M, 2, 2M, 3R, 3B, and 4
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Medical Device Classes in relation to design conrtrol
- ISO13485 - design controls
- Canada - I (no need), II, III, IV
- U.S. - I (only need for software), II, III
- EU - I, IIa, IIb, III
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Canadian Classification
- Rule-Based Classification
- active device: source of nrg other than human body or gravity
- active diagnostic device: info for the purpose of detection or monitoring
- active therapeutic device: supports, modifies, replaces, restores
- invasive device: contact with eye or penetrate
- Particular rules apply to particular devices.
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FDA Device Classification
- Substantial Equivalence: same intended use AND tech characteristics OR same intended use AND FDA does not raise new questions of safety & effectiveness
- Class I: general controls, min potential for harm
- Class II: special controls, general controls insufficient
- Class III: premarket approval, special controls insufficient
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contents of 21CFR800-898
- labelling
- medical device reporting
- investigational device exception (IDE): get this for pre-approved device before allowed to get clinical test data
- market clearance
- premarket approval of medical devices
- QSR (quality system regulation)
- medical device classification and groups
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ISO13485 and 21CFR820 elements (20)
- management responsibility
- ID & traceability
- document control
- customer-supplied product
- tool control
- non-conforming material (lock up so nobody uses it)
- quality records
- corrective & preventive action
- handling, storage & packaging
- quality system
- design control
- purchasing
- contract review
- testing
- labelling
- internal audits: "say what you do, do what you say"
- training
- statistical analysis
- servicing
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why need design control
- ensure safety & efficacy through controlled design process
- ensure successful & efficient implementation
- U.S. 21CFR820.30 required for classes II, III
- Canada ISO13485 section 4.4 required for classes III, IV
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waterfall model
 - output feeds into input
- separate overlapping phases
- risk management is a 'separate' parallel process
- documentation part of design process
- not realistic b/c design process not linear but iterative
- usually limited on time
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documentation process in design control
DHF (design history file) contains DMR (device master record, everything needed to know about service & manufacturing device) + DHR (device history record, this is what i did, materials that i used)
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elements of QA
- design control: planning, input/output, verification & validation, hazard analysis, review
- documentation & documentation control
- corrective/preventive action
- consistency of process
- management commitment
- proactive rather than reactive
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