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

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

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

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 www.fda.gov/medicaldevices

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

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. 

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 862 -- CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Subpart B--Clinical Chemistry Test Systems Sec. 862.1345 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.

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?

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)

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

“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

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?

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

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

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)

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?

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!!!!

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 http://www.fda.gov/MedicalDevices/ DeviceRegulationandGuidance/Overview/

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

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) c.j.lord@ieee.org http://www.blueridgetechnc.com