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Insight Report No.11 Vol. 4

RISK MANAGEMENT: HAZARD ANALYSIS AND FMEA

Hazard Analysis and Failure Mode and Effects Analysis (FMEA) are two tools used to manage risk in the development of medical devices. There are many people who do not understand these tools and are not aware that they are two separate and distinct tools. This insight report will try to provide a definition of each and the differences between the Hazard Analysis and FMEA.

HISTORY OF RISK MANAGEMENT

Formal risk management techniques were developed for the nuclear and defense industries in the 1940’s. The petroleum and chemical process industries were among the first commercial industries to adopt these techniques in the 1960’s. In the 1980’s the automotive industry joined in. In 1990 the FDA first established risk management regulations and standards for the medical devices industry.

DEFINITIONS

Hazard Analysis is the detailed qualitative examination of the device from the perspective of the user. It considers the interface of the device with the user. It ignores the internals of the device and what may happen internally in the device to cause an external hazard.

FMEA is a detailed examination of each internal component. The FMEA considers how each component might fail and the effect of each failure on system operation. Each device is not composed of independent parts; they are all linked. They may be composed of electromechanical mechanisms, sensors, control electronics and software. Failure of one component may lead to other internal failures. The FMEA leads to the generation of a critical component list.

Hazard Analysis is a “top-down” approach while FMEA is a “bottoms-up” approach. They are complementary to each other and together constitute a risk management program. Each document should be approved and controlled. The FMEA is more time consuming and requires more sophisticated technical input than the hazard analysis. Typically the hazard analysis is conducted early in the design process and updated as the design progresses. The FMEA is conducted when details of the design are sufficiently firm, usually at the first prototype build and is then updated as the design progresses. Be aware that both are a basic requirement of the FDA Design Control process.

HAZARD ANALYSIS

The hazard analysis begins with definitions of all possible hazards to the user that might occur (initially no consideration is given to probability of this event happening). It is helpful to distinguish between a hazard and the effect of a hazard; for example a hazard would be “exposed wiring”; the effect of the hazard would be “electrical shock”. The hazard analysis is usually presented in table form for easier reading

Next the possible cause or causes of the hazard are identified. Each hazard could have multiple causes. For example consider an IV bag. A possible hazard is an IV bag falling . Possible causes are:

1. IV stand imbalance

2. Bag clamp failure

3. Bag failure

At this point causes are kept general. Specific design elements are not identified.

Responses for each cause are now identified in as much detail as needed to provide direction to the design team. For example, for cause to 1 above the response might be: increase stand base diameter.

A simple hazard analysis could end at this point. For a complex system further analysis is usually conducted. Probability of occurrence and severity of the hazard are factored into the analysis. Probabilities are divided into several categories from frequent to improbable and severities are also divided into categories from catastrophic to negligible. Each hazard is assigned an identification number and a probability as well as a severity ranking. A table is created with probability categories in the leftmost column and severities in the top row. Each hazard identification number is placed in a position in the table determined by it’s ranking.

This table gives a visual method to determine which hazards require corrective action and helps to determine priorities of corrective action. See the example table below. Hazard 4 can probably be addressed by means of a label warning while hazard 3 definitely requires re-design work. Hazard 3 would be fixed before hazard 1.

FMEA

FMEA is generally presented in a table that shows each component’s failure mode, it’s cause, and the corresponding effects. A component failure can cause a linked component or subsystem to fail. From the FMEA (or included as part of it), methods to control or indicate failures can be developed. Design changes may be made to eliminate a failure or alarms might be included in the design. A sample table is shown below:

There are other methods of performing an FMEA, where each failure is scored based on the following: chance of occurrence, chance of detection, severity of the incident if occurred. The score ranked on a 1-10 bases with 10 being the worse condition and 1 being the best condition. Then for each failure the scores are multiplied and a final score given for each component failure with the highest score being 1000 (10x10x10) and the lowest a 1 (1x1x1). The group conducting the FMEA uses an arbitrary number where they feel the potential risk of the failure is minimal, usually around 100. Any score above that number would have to be addressed to reduce the risk, i.e. redesign, alarms, or if no fix is available, additional warnings on the device, on the label or in the user manual.

Both the FMEA and the Hazard Analysis are two tools that have to be made part of any firm developing new products. It has become an expected part of any device release. With a fully documented FMEA and Hazard Analysis could only result and problems down the road.

Other uses of the FMEA in future Insight Reports.

For more information on either the FMEA or the Hazard Analysis email us at: FMEA@mdiconsultants.com.

Next Insight Report - to be announced.

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