Page 81 - Safety Risk Management for Medical Devices

60 Safety Risk Management for Medical Devices

each entry in each cell of the matrix by its severity and occurrence rankings. In other
words:
Score 5 P (N 3 S 3 O) for all cells:
where,

N 5 the entry in the cell
S 5 the severity ranking for that cell
O 5 the occurrence ranking for that cell

A lower score would be better than a higher score.

11.3.2 Other considerations for risk reduction end-point
Bordwin in Ref. [23] states “The law books are filled with cases alleging defective
design of equipment that plaintiffs claim caused injury or death. “; “A product is
defective when.. .it is defective in design.. .. A product is defective in design when
the foreseeable risks of harm posed by the product could have been reduced or
avoided by the adoption of a reasonable alternative design by the seller.. .”
It is very likely for most medical device companies to face legal challenges at some
point, and have to defend themselves in liability lawsuits. As quoted earlier, in such
lawsuits the assertion would be that the manufacturer did not take reasonable measures
to reduce the risk of Harm from the device. Having a rational, defensible, and docu-
mented methodology to determine risk reduction end-point, would be very valuable
in the legal defense in such lawsuits. In particular, as Ref. [22] states “safety of the
product must not be traded off against business perspectives.”

11.4 HAZARD IDENTIFICATION

The manufacturer is expected to identify all risks due to the use of the medical
device. This requires knowledge of all the Hazards associated with the use of the
device. While it is difficult to claim completeness, the use of a standardized CHL
enables you to claim that you are as complete as possible. See Section 11.5 for further
details on the CHL and how to create it.
The Hazard identification phase also entails identifying the Causes of the Hazards
and the likelihood of occurrence of the Hazards. This is facilitated by the use of the
technique of FMEA. See Section 12.4 for details on FMEAs.
A major source of Hazards is the interoperability of interfacing parts. Most medical
devices are comprised of part that connect and interoperate with each other. These
include mechanical, electrical, and informational interfaces. Additionally, you should
consider interfaces with the outside world.