1. External Defibrillator Design Deficiencies And Their Impact On Users and Caregivers Al Taylor Director, Division of Electrical and Software Engineering CDRH Office of Science and Engineering Laboratories December 15, 2010

2. 2 How serious is the problem? External defibrillators save many lives, and malfunctions are relatively rare, even for those defibrillators that were recalled. No one should think twice about using for a defibrillator if the situation calls for one.

3. 3 How serious is the problem? For some devices, adverse events are caused by design deficiencies that were foreseeable and preventable. Any preventable injury is one too many. Additional adverse events are averted by timely intervention of caregivers.

4. 4 How serious is the problem? Many failure investigations reported by manufacturers have misidentified the root cause of adverse events Independent FDA failure investigations repeatedly identify deficient product design (i.e., poor engineering) as causing or contributing to many adverse events.

5. 5 One recent example … it is not our intent to focus attention on either the manufacturers or the product involved. Instead, we would like you to focus on the nature of the design error that was made, and the consequences for users and patients. In this case, and quite a few others that we don’t have time to show you today, corrective actions have minimized the potential for harm.

6. 6 One recent example Automatic external defibrillator was reported to misdiagnose the ECG waveform in some instances The result could be failure to shock when warranted, or the converse — delivering a shock to a patient who did not require one Manufacturer never explicitly identified the root cause, but their testing pointed to electrical noise (interference) as the root cause and they proposed to modify the device software to filter out the noise

7. Differential Amplifier VoVo t t V 1 or V 2 VoVo Chest V noise V2V2 V1V1 100k 6.2k 100k 6.2k

8. 8 1 inch

9. Tolerance Analysis

11. 11 Was the error preventable? The principles of op amp circuits are taught to every undergraduate electrical engineer. Verification testing of the amplifier circuit should have detected poor performance. The cardiac monitoring standard (AAMI EC-13) addresses performance of waveform diagnosis in the presence of common-mode noise. The deficiency should have been detected during the design review.

12. 12 More generally … Many design issues arise from selecting components that are unsuitable for their intended use in the device. –The component data sheets are critical. –The design engineer must understand all of the characteristics of each component and how those characteristics affect the performance of the finished device.

13. 13 More generally … Many manufacturing defects arise from inadequate design of the production processes. –Foreseeable errors on the shop floor have to be anticipated and prevented by design.

14. 14 More generally … Any component in the device can be subject to a design or manufacturing deficiency. –Qualify component suppliers –Actively monitor performance of suppliers –Establish business relationships that facilitate issue management when problems do arise

15. 15 More generally … Most of what were are talking about here is Quality Management System basics: design controls, production controls, purchasing controls. But it’s not sufficient to have a well-documented QMS. The manufacturer must also make sound engineering decisions.

16. 16 More food for thought … Consequences of poor design may be felt by patients, caregivers, and people who maintain and service pumps. Some design errors can be corrected readily, but many cannot. Ultimately, the cost of poor quality affects us all.

17. 17 Conclusion We hope this short presentation helps you to understand our concerns. We seek to engage with all stakeholders to seek constructive solutions.