Page 130 - Safety Risk Management for Medical Devices

Risk Analysis Techniques 109

Table 12.9 PFMEA detectability ratings
Detection Criteria (Det)

Category Rank Qualitative criteria Quantitative
criteria
Undetectable 5 Physics-of-Failure not understood | No ,10 23
detection opportunity (e.g. no inspection, or
no means for detection) | Countermeasures
not possible

Low 4 Failure is very difficult to detect | Opportunity ,10 22 and
23
for detection is low (e.g., very low sampling $ 10
for inspection) | Countermeasures are
unlikely
Moderate 3 Failure is moderately detectable | Opportunity ,10 21 and
for detection is moderate (e.g. 10% sampling) $ 10 22
| Countermeasures are probable
High 2 Failure is very detectable | Opportunity for , 9x 10 21
detection is high (e.g. 100% visual inspection) and
| Countermeasures are likely $ 10 1
Almost Certain 1 Failure is obvious | Opportunity for detection is $ 9x10 21
almost certain (e.g., 100% instrumented
inspection) | Countermeasures are certain

Table 12.10 Process Failure Modes and Effects Analysis RPN table

12.8 USE/MISUSE FAILURE MODES AND EFFECTS ANALYSIS

UMFMEA is a tool to analyze the effects of failures in the use of a medical device,
and also the effects of misuse of the device. We distinguish Misuse from Use Failure.As
defined in Section 8.1, a Use Failure is the failure of a User to achieve the intended
and expected outcome from the interaction with the medical device. A Use Failure is
not something that the User intends, but Misuse is intended by the User.