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Speeding Products to Market Using Risk Analysis
Risk. This is a four letter word that represents something that many of us prefer to avoid, yet can’t. Every day we are confronted with risks. We analyze risks and make decisions often without even realizing it.
“ Should I leave the windows open? There is a chance of rain.” “Should I lock the car? I will be only a few minutes.” “Should I take the highway? It is usually quicker but sometimes it can be much longer.”
The more undesirable the possible outcome the more careful we are in our decision making process. The worst risk we are subjected to is the one we are not aware of or are misinformed about. This is typically where the most harm and damage is done. Modern society recognizes this and as a result we have laws, regulations and standards intended to minimize harm and damage. In the medical device industry risk analysis is required by many regulatory authorities. Analysis of risks associated with products is taken quite seriously. Many companies have learned the value of conducting thorough risk analyses earlier in the design process. There are many different methods for analyzing risks associated with medical devices. One of the more commonly used methods is Failure Mode Effects Analysis.
BACKGROUND What is FMEA? Purpose Application Uses ANALYSIS Failure modes Effects Severity Probability of occurrence Current design controls Probability of detection Risk priority number Recommended actions Questions to ask TYPES OF HAZARDS Energy Biological Environmental Usage Functional/Maintenance BACKGROUND What is FMEA? Failure Mode Effects Analysis (FMEA) and Failure Mode Effects and Criticality Analysis (FMECA) are disciplined methods of analysis intended to identify and minimize unwanted performance or potential failures which have significant consequences affecting a device’s or system's performance in its intended application. FMECA is an extension of FMEA that includes in the analysis a consideration of the severity, or criticality, of the consequences of a failure. Both qualitative and quantitative analysis is required and these compliment one another. FMEA and FMECA can be performed in either a top-down approach or a bottom-up approach. A top-down approach starts with an outcome and works toward the cause(s) at a lower level. A bottom-up approach starts with an event at a low level and works towards the final outcome. There are two main types of FMEA; Design FMEA and Process FMEA. As you may have guessed Design FMEA concerns itself with the design while Process FMEA concerns itself with workflows. This discussion will focus on design FMEA/FMECA. Due to the scope and the multi-disciplinary nature of the FMEA/FMECA, a team effort is needed to produce the desired outcome. There are many different ways to structure an FMEA/FMECA. This discussion is intended only as in introduction to the general process. A good start to learning more on this topic is to read EN 14971 2000 Medical Devices - Application of Risk Management to Medical Devices . Purpose The purpose of the design FMEA is to serve as a means for evaluation of the effects and the sequences of events caused by each identified failure mode, from whatever cause, at various levels of a system's functional hierarchy. Through this process a number of observations are made including but not limited to: significance of each failure or its severity, critical component identification, reliability and/or safety of design or process, probability of an event, detectability, diagnoseability and testability. FMEA can be used as a tool to improve safety, increase quality, improve reliability, lower costs, and decrease liability. Application The analysis can be applied to new or existing designs and processes. The most gain can be obtained on new design and process analysis. Components, assemblies, systems, and processes can all be subjected. Even service organizations can utilize the techniques in an effort to provide their customers with better service. Uses A number of uses that the analysis can produce are: • determining the need for redundancy • designing features which increase the probability of "fail safe" operation • design simplification • determine demands placed upon materials, components assemblies, and systems • disclose safety hazard and liability problem areas • ensure regulatory compliance • determine safe operating limits and device lifetimes and failure rates • develop maintenance/service requirements • prioritize areas for improvement • establish need for data recording and monitoring during testing and use • development of troubleshooting guides • facilitate/support the determination of test criteria/plans/diagnostic procedures • forum for discussion of alternate designs • enhance the knowledge and understanding of the behavior of item(s) or process • facilitate communications • reduce scrap & increase yield ANALYSIS Failure modes The manner in which a part, assembly, or system could potentially fail to meet its requirements or fail to function. It is also what you may reject the item for. Effects The potential non-conformance stated in the terms of the next assembly or system performance (from the customer's perspective). Causes The potential reason(s) behind a failure mode, usually stated as an indication of a specific design or process weakness. Severity A qualitative assessment of the seriousness of the effect of the potential design failure mode as viewed from the perspective of the customer, system, or government regulation. The severity applies to the effect of a failure mode. The severity ranking can be reduced only through a change in design. The following table is a description of a ten level severity ranking system. The number of levels in a ranking system is not as important as creating an effective strata of severities. Aspects of customer satisfaction are indicated in the table to illustrate the ability of the analysis to be utilized for more than human safety.
Probability of occurrence A qualitative or quantitative assessment of how frequently the failure mode is projected to occur as a result of the specific cause. Where possible, probability of occurrence is based on available data on the specific cause.When number of failures due to specific cause cannot be estimated then it is acceptable to examine similar components or systems. If it cannot be estimated, the probability should be considered high. The ranking can be reduced by improving engineering specifications and/or requirements. The following table is a description of a ten level probability of occurrence ranking system. As noted in the severity ranking description, the number of levels in a ranking system is not as important as creating an effective strata.
Current design controls The various design features that are put in place throughout the system to ensure proper performance. Controls can include processing steps, test procedures, characterization tests, detection circuitry or any means that can be used to prevent or detect a potential failure before an undesirable outcome occurs. Probability of detection A qualitative assessment of the probability of the design control to detect a potential cause or mechanism of failure.If it cannot be estimated, the ranking should be considered high. The ranking can be reduced by adding or improving design evaluation techniques to increase the ability to detect the potential failure before it results in an undesirable outcome. The following table is a description of a ten level probability of detection rankng system. Some FMEAs do not use a separate probability of detection number. In these analyses the probability of detection is “built into” the probability of failure rating
Risk priority number The risk priority number (RPN) is the product of the severity, occurrence, and detection rankings. The RPN helps to prioritize potential failures and is used to rank potential design deficiencies and/or liability issues. The goal is to reduce RPNs through a reduction in severity, occurrence, and detection rankings. The analysis review team should establish a maximum RPN number. Risks that remain above the maximum RPN number are considered residual risks. Other evaluation criteria may also be used to identify residual risks. Risks that are below the maximum RPN number but meet other criteria such as those having a criticality of Sever or higher may a also be considered residual risks. Recommended actions Actions that are suggested to help reduce the RPN and residual risks. There will be times when the RPN and residual risks cannot be reduced by any reasonable means. Recommended actions may still be offered to increase the awareness of the item. Some Questions to ask A number of questions to ask yourself when performing an FMEA or FMECA are listed below: Who is the intended user? What is the required skill of the user? What is the required training of the user? What is the environment it is to be used in? Who does the installation/setup? Can the patient influence the use of the device? Is there any invasive contact? Are there any contacted parts? What is the duration of contact? What is the frequency of contact? What type of energy is delivered if any? How is the delivered energy controlled? What is the quantity of energy delivered? What is the quality of energy delivered? What is the time function of the energy delivered? Are any devices sterilized by the user? Are there any devices sterilized by the manufacturer? What type of sterilization is used? Are there any single use devices? Can failure be detected before hazard occurs? Can failure be eliminated by manufacturing controls or preventative maintenance? Will misuse increase likelihood of failure? Can alarms be added? What is the number of multiple uses for the device? What is the shelf/storage life? What is measured? What is accuracy? What is precision? Is device to be used with other devices or drugs? Does device produce unwanted radiation? Is device influenced by unwanted radiation? Is device influenced by environmental conditions? What are the essential accessories or consumables associated with the device? Who calibrates? How often? Who maintains the device? How often? Any disposal or by-product issues? Any long-term cumulative effects? SOME TYPES OF HAZARDS Energy Electricity Heat Mechanical force Ionizing radiation Non-ionizing radiation Electromagnetic fields Moving parts Suspending masses Patient support device failure Pressure vessel rupture Acoustic pressure Vibration Biological Bio-burden/bio-contamination Bio-incompatibility Incorrect formulation Toxicity Infection Pyrogenicity Hygienic safety Environmental Electromagnetic interference Inadequate supply of power Likelihood of operation outside prescribed environmental conditions Incompatibility with other devices Waste products
UsageInadequate labeling, instructions, specifications Over complicated instructions Unavailable or separate instructions Use by unskilled or untrained Human error Insufficient warning of side effects Inadequate warning of hazards likely with reuse of single use devices Incorrect measurements Incorrect diagnosis Erroneous transfer of data Misrepresentation of results Functional/Maintenance Inadequacy of performance characteristics for intended use Lack of maintenance specifications Lack of maintenance Lack of determination of end of device life Inadequate packaging
Optimum Technologies, Inc. offers regulatory affairs consulting on all aspects of medical device development and manufacturing. Contact us to obtain a quote for services.
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