1 Overview of Standards for External Defibrillators: Role of FDA Charles Ho, Ph.D. FDA/CDRH/ODE

2 Outline 1.Why use standards? 2.FDA’s role in standards 3.List of major standards 4.Limitations of standards

3 1. Why use standards? Standards facilitate communications in pre-market reviews. Standards provide test protocols with pass/fail criteria, which form a common language between manufacturers and FDA for substantiating claims.No need to re-invent the wheel each time. Standards provide test protocols with pass/fail criteria, which form a common language between manufacturers and FDA for substantiating claims. No need to re-invent the wheel each time.

4 Example: To claim adequate battery capacity to power a defibrillator Reference: ANSI/AAMI DF80, clause Protocol: At O°C, the battery should enable the defibrillator to deliver at least 20 shocks at the maximum shock energy. O°C test is more demanding than room temperature test.] [O°C test is more demanding than room temperature test.]

5 Standards also facilitate standardization of device specifications among device manufacturers. May lead to standardizing certain features, like pad connections and the user interface. But need to be in sufficient detail to allow interpretation by both design engineers and FDA.

6 Remember, most standards concerning external defibrillators are voluntary. The only mandatory standard for an external defibrillator is the Performance Standard for Electrode Lead Wires and Patient Cables, 21 CFR 898.

7 2. FDA’s Role in Standards Although FDA had been involved in the development and use of medical device standards for decades, the Food and Drug Administration Modernization Act (FDAMA) of 1997 formalized the process. * Above statement adapted from FDA website.

8 FDA liaisons attend standard committee meetings, participate in discussions and vote on proposed standards, in order that the resultant standards may be more acceptable to both the industry and the FDA.

9 Dr. Oscar Tovar is our Primary Liaison for standards on external defibrillators at the AAMI DF Committee and the IEC TC 62/SC 62D/MT 19 Committee. Dr. Richard Gray is the Alternate Liaison.

10 The FDA has only one vote in each standards committee, just like any other entity. Thus, some standards may not be 100% acceptable to FDA.

11 In that case, FDA recognizes only the parts of a standard that FDA agrees with, and declines to recognize the parts that FDA does not agree with.

12 Recognition of a standard By recognizing a standard, or parts of a standard, FDA indicates that we have reviewed the standard and found it mostly acceptable for substantiating claims made in a premarket submittal.

13 Example: A 510(k) claiming adequate battery capacity provides a test report using AAMI DF80, clause And FDA can review this test very quickly.

14 If a manufacturer chooses not to comply with an FDA recognized standard, or tests a defibrillator using clauses in the standard that FDA declines to recognize, FDA will still review the premarket submittal on a case by case basis.

15 Consequently, FDA will have to review the unrecognized clauses in a recognized standard, or the unfamiliar test protocols in a unrecognized standard from the ground up. This may generate a lot of basic questions to clarify terms or rationale for a certain test protocol, usually resulting in more work for both the manufacturer and FDA.

16 3. List of Major Standards for External Defibrillators (non-exhaustive list)

17 Hardware  ANSI/AAMI DF80: Medical electrical equipment - Part 2-4: Particular requirements for the safety of cardiac defibrillators (including automated external defibrillators) -- the most commonly used standard in submittals on external defibrillators -- covers most hardware safety and effectiveness specifications, except waveform effectiveness IEC counterpart:  IEC : Medical electrical equipment - Part 2-4: Particular requirements for the safety of cardiac defibrillators and cardiac defibrillator- monitors

18 For general safety:  IEC : Medical Electrical Equipment - Part 1: General Requirements For Safety 1: Collateral Standard: Safety Requirements for Medical Electrical Systems For electromagnetic compatibility (EMC):  IEC : Medical Electrical Equipment - PART 1: General Requirements For Safety 2. Collateral Standard: Electromagnetic Compatibility - Requirements and Tests

19 Biocompatibility [for defibrillator electrodes (pads or paddles):]  ISO – 5: Biological evaluation of medical devices -- Part 5: Tests for in vitro cytotoxicity  ISO Biological evaluation of medical devices — Part 10: Tests for irritation and delayed-type hypersensitivity (sensitization)

20 Environmental testing:  IEC : Environmental testing - Part 2-27: Tests - Test Ea and guidance: Shock  IEC : Environmental testing - Part 2: Tests - Test Fc: Vibration (sinusoidal)  IEC Degrees of protection provided by enclosures (IP Code). [protection against rain and dust] For sample list of standards, see handout.

21 4. Limitations of standards Standards do not cover every aspect of the external defibrillator. For example, there is no clinical or animal study protocol in the AAMI DF80 standard. (However, an informative annex DD in DF80 has some historical notes on clinical studies.)

22 Further, it is widely accepted that biphasic waveforms are superior to monophasic waveforms and result in improved patient survival. But the standard that covers basic safety and effectiveness requirements, AAMI DF80, does not prohibit monophasic waveforms. A new defibrillator with this old technology can still claim compliance with DF80.

23 Lastly, some standards permit a large leeway in designing the defibrillator, so that performance could vary considerably from manufacturer to manufacturer. An example is the difference between delivered energy and selected energy in a defibrillator.

24 [From DF80, clause ] Delivered energy = shock energy actually delivered to a patient [From clause ] Selected energy = energy intended to be delivered, as determined by the setting of a control determined by the setting of a control Usually, this is the energy shown in the energy dial of the defibrillator front panel.

25 However, the selected energy is specified for the 50 ohm load only. For all other loads, the manufacturer just has to specify the selected energies in the device manual. Additionally, the verification test protocol allows a ± 15% tolerance in testing the measured delivered energy against the specified selected energy. [clauses 6.3 aa, aa and 50.2]

26 These two layers of tolerance combine to allow delivered energy values that may be very different from the selected energies on the energy dial, for loads other than 50 ohm. Yet not every patient is a 50 ohm load to the defibrillator. Still compliant with DF80!

27 Conclusion This presentation has briefly described FDA’s use of standards for external defibrillators, and the standards’ limitations. It is hoped that everyone can keep these in mind as we move forward in this field.