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U.S. Department of Health and Human Services

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FY 2000 Failure Analysis Of Electronics In Medical Devices

OST applies readily available tools and methods to the laboratory evaluation of medical device performance. OST also applies analytical tools to problems of medical device reliability. These programs are directed at identifying generic device electrical engineering problems and their solutions. The principal laboratory activities are to design and develop specialized test equipment, evaluate failed medical devices, and develop test methods. Areas of particular laboratory interest include microcircuits, batteries, and electrical fires.

Regulatory Support - Forensics
Key words: electronics, forensics, regulatory support, fire

OST provided laboratory forensic support for several FDA regulatory actions. In one, an OST engineer played a significant role in a case involving the explosion of a lithium sulfur dioxide battery in a portable defibrillator. The battery in question used a newly emergent technology. This technology offers significant performance advantages over more established battery chemistries, but hazards associated with the new product were not well understood by the manufacturer. OST's investigation revealed that at least one other manufacturer of portable medical devices has grappled with these issues.

In another compliance case, one involving an infusion pump, it was determined that defective battery "gas gauge" software caused a rechargeable battery to be depleted to the point that physical damage occurred in one or more cells, resulting in premature failure of the battery. An OST engineer participated in an on-site inspection of the firm, which prompted a product recall.

OST engineers provided regulatory support in several other cases involving electrical safety. In one case, OST developed a test apparatus for assessing the compliance of medical device connectors with the CDRH Standard for Electrode Test Leads and Patient Cables. In another case, cable assemblies from a surgical device were tested for compliance to IEC 60601-1. In a third case, OST investigated a recall situation involving a neurological testing device that was manufactured by both a U.S. and Canadian firm under a license agreement. The U.S. firm determined that the design was not compliant with electrical safety provisions of IEC 60601-1 and instituted a recall on that basis. The Canadian firm disagreed with this assessment and declined to recall. OST determined that the product was indeed non-compliant. A fourth case involved a complaint brought by a competitor against a cardiac assist device, in which it was alleged that the device violated an electrical safety standard to which compliance was claimed. OST determined that the design did not violate the standard and the manufacturer was exonerated. In a fifth case, OST assisted in the field investigation of an implantable defibrillator. Capacitor quality and aging issues were addressed.

Premarket Support - Scientific Evaluations
Key words: electronics, forensics, regulatory support, fire, standards/guidance

OST engineers consulted on a premarket review case, involving a novel technique for securing bone staples. The staple was designed to be inserted into pre-drilled holes in the bones to be fastened. The device in question passes electrical current though the staple, causing it to become hot. The tines of the staple are designed to deflect inward when heated, permanently securing the staple and fixing the joint. OST was to assess whether UL Standard 2601-1 was adequate to assure safety of this device. It was determined that UL 2601-1 did indeed apply to this device, and that the device appeared to be compliant. However, the issue of possible tissue necrosis due to heating of the staple is a clinical issue and thus outside the scope of the standard. OST staff carefully explained the limits of applicability of the standard and suggested how the clinical issues could be clarified.

Quality Management
Key words: quality systems

An OST engineer has worked with senior CDRH management to begin implementing a Center-wide quality plan. OST has advocated applying the concepts of design control, quality systems, and risk management to a variety of regulatory problems. Positive impact by OST on the direction and outcome of several reengineering efforts, on the science review, and on several premarket guidance documents has been achieved. Specific examples include the following:

  • A tutorial was presented on the principles of design control in the Staff College Quality Lecture series. Part of this presentation focused on the need for organizations to develop an integrated system of quality management processes that encompasses product quality, risk management for safety, environmental management, regulatory requirements, and business decision-making; 
  • Technical support was provided to the FDA Laboratory Accreditation Committee on a number of issues, including estimating the cost of implementation and formulating a training plan;
  • A consultation was provided to the Office of Regulatory Affairs on implementing a document control system; 
  • Consultations were provided to various field investigators on a variety of quality system issues involving design controls, corrective and preventive actions, and calibration of test and measuring equipment. The focus of OST's contribution in these cases is reconciling the general requirements of the quality system regulation with the specific practices of the electronics industry;
  • OST provided consultation to several CDRH reengineering committees to help them to validate reengineered processes. Most notably, work with the QSIT Reengineering Team has helped to ensure broad acceptance of the Quality System Inspection technique; and 
  • Design control concepts were incorporated into a new guidance document covering home uterine activity monitors. This guidance document describes a means by which manufacturers can establish substantial equivalence to a predicate device. Designating this guidance document as a "special control," in the language of the Safe Medical Device Act of 1990, permitted home uterine activity monitors to be downgraded from Class III to Class II. By following the guidance, manufacturers can minimize the effort required to prepare the premarket submission and significantly streamline the Agency’s review. In response to this request for assistance, OST developed plain language clarifying the distinction between a premarket review of design information and a quality system review of the same or similar information. Now that design controls are firmly ensconced in the quality system inspection, premarket reviewers may avoid covering the same ground as covered by quality system investigators.

Additionally, OST engineers led an effort to lay the groundwork for a quality management system within the Office of Science and Technology. This included preliminary training for managers in quality management system concepts, performing a gap analysis to assess the degree to which the Office’s existing management systems satisfy the requirements of ISO 9001, and developing a detailed plan and cost estimate to implement a compliant quality management system.

Risk Management
Key words: risk management, training

OST developed a plan for training Center staff in the principles and practices of risk management, how those principles and practices are applied by device manufacturers, and how risk management information can be used to expedite the review process. This has been a major undertaking affecting ORA, OC, and ODE. First, OST staff worked with ORA in developing a set of computer-based training modules in technical risk management for field personnel. OST developed the outline for the first training module, identified CDRH experts in human factors and software hazard analysis to work on modules, and has provided an expert to write the module on risk management and the Quality System Regulation. In addition, OST participated in the ISO/IEC 14971 Joint Working Group on Risk Management for Medical Devices.

Key words: reliability, dependability

For the past several years OST has provided the representative to the IEC TC 56 on Dependability. This work has resulted in the FDA recognition of IEC 61812 Analysis Techniques for Reliability - Failure Mode and Effects (FMEA). FMEA is the primary risk analysis technique used by medical device manufacturers, and recognition of IEC 61812 will promote harmonization in this important area with regulatory organizations in other countries. IEC TC 56 has now moved on to revising IEC 60300-3-1 on Dependability Analysis Techniques, the purpose of which is to increase its relevancy to modern dependability programs of the type used by the vast majority of medical device manufacturers. Issues in medical device reliability and dependability have pointed to the need for a new laboratory in OST concerned with issues of reliability -- a laboratory capable of analyzing data coming from a variety of sources and generated under a variety of test conditions. OST tested the concept of a Reliability Laboratory when, in support of DCRND in the review of an IDE and PMA for two Left-Ventricular Assist Devices (LVADs), it provided technical analyses of the company's reliability programs and evaluation of reliability data.