1. Introduction to Medical Electronics
Day 2: Medical Device Safety, Reliability, and Regulatory Issues
May 7, 2013 Charles J. Lord, PE President, Consultant, Trainer Blue Ridge Advanced Design and Automation

2. This Week’s Agenda
5/6 Medical Device Overview 5/7 Safety, Reliability, Regulatory Issues 5/8 Communications Part 1 5/9 Communications part 2 5/10 Medical Data Storage

3. This Week’s Agenda
5/6 Overview 5/7 Safety, Reliability, Regulatory Issues 5/8 Communications Part 1 5/9 Communications part 2 5/10 Medical Data Storage

4. Medical Device Regulations
Examples here are US FDA
Other countries have similar structure
Underlying issues – RISK MANAGEMENT and QUALITY ASSURANCE
The previous Good Manufacturing Practices are now replaced with the Medical Device Quality Systems Manual
All FDA laws are 21 CFR 620-up

5. Classes of Devices
There are three basic classes of devices I-III, with increasing levels of regulation and requirements for testing / certification
Best practices are to adhere to the top level internally
Documentation
Traceability
Accountability

6. Classes of Devices (2)
Class I devices are deemed to be low risk and are therefore subject to the least regulatory controls. For example, dental floss is classified as Class I device.
Class II devices are higher risk devices than Class I and require greater regulatory controls to provide reasonable assurance of the device’s safety and effectiveness. For example, glucose meters are classified as Class II devices. 
Class III devices are generally the highest risk devices and are therefore subject to the highest level of regulatory control. Class III devices must typically be approved by FDA before they are marketed. For example, replacement heart valves are classified as Class III devices. 

7. Finding your class
TITLE 21--FOOD AND DRUGS CHAPTER I--FOOD AND DRUG ADMINISTRATION DEPARTMENT OF HEALTH AND HUMAN SERVICES SUBCHAPTER H--MEDICAL DEVICES PART CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Subpart B--Clinical Chemistry Test Systems Sec Glucose test system. (a)Identification. A glucose test system is a device intended to measure glucose quantitatively in blood and other body fluids. Glucose measurements are used in the diagnosis and treatment of carbohydrate metabolism disorders including diabetes mellitus, neonatal hypoglycemia, and idiopathic hypoglycemia, and of pancreatic islet cell carcinoma. (b)Classification. Class II.

8. Usage
The FDA looks at two issues to classify a medical device – its function and its intended (stated) use. A good example is an electrocardiograph (EKG or ECG):
If the device is for home use, primarily for tracking fitness, it will be classified as a Class II (or possibly Class I) device
If the device (can be the same electronics!) is used for monitoring patients in an ICU, it is now a Class III device.
SO – if you developed the first device, and want to make it part of the second – Did you keep proper records or do you need to start anew?

9. Design Criteria
Again, the risks need to be addressed in medical electronics:
Direct risk to patient (e.g. current through the body, either direct or through power supplies or other sources – even from possible misuse)
Risk of erroneous values (too high or too low a reading, resulting in improper action to treat or not treat)

10. Direct Risk Power supply safety and isolation
Current leakage detection and elimination
Test V/I limitations
Active shutdown
Temperature / pressure / other parameter sensing accuracy and limits
Pressure / travel limits on mechanical actuators

11. “Indirect” Risk Reliability, Repeatability, and Accuracy of readings
Verify alarm settings
Positive notification of failure detection
Verification of proper usage (if possible)
Readability of output (what if an LCD segment fails?)
Verification of data sent to another device

12. Sensors What is the reliability and accuracy of the sensor?
How do environmental changes affect the above?
Can the sensor cause harm to the patient?
Can the sensor affect the other sensors in the device – or be affected?
What is worst case of a sensor failure or bad reading? Can we detect this?

13. Analog 50/60 Hz rejection Filtering of other outside fields Drift CMRR
Gain stability
Filtering – again, accuracy!
Shielding and PCB layout can be critical!!

14. A/D – D/A Actual effective bits Drift Averaging
Accuracy, repeatability – how accurately can it be calibrated?
MUX and S/H issues
Speed vs all of the above

15. Controllers
Hardware issues – stability over voltages, clock and timing
COP and LV behaviors
Noise immunity for I/O
Overall reliability (depending on class)
Often - Power consumption! (and wake timing / performance)

16. Software (21 CFR Part 11) Clearly written code! What-if covered
RTOS, driver source may be needed
Test, Test, Test
Fail-safe for code faults
How are stack, data, segment, branch faults handled?

17. System What can happen – and more Blood, Sweat, Tears, and more
Temperature and humidity
G forces
Users use and mis-use
Test Test Test
Document!!!!

18. Design Process
Define what your device does and how it will be used (all intended ways)
Look up functionality and use in FDA guidelines
Determine the class of the device
Follow the guidelines for that class
Know exceptions – may not need announcement or other special prep
Design your product accordingly
DeviceRegulationandGuidance/Overview/

19. This Week’s Agenda
5/6 Overview 5/7 Safety, Reliability, Regulatory Issues 5/8 Communications Part 1 5/9 Communications part 2 5/10 Medical Data Storage

20. Please stick around as I answer your questions!
Please give me a moment to scroll back through the chat window to find your questions
I will stay on chat as long as it takes to answer!
I am available to answer simple questions or to consult (or offer in-house training for your company)