Evaluation (Validation and Verification) - Medical Device Design: Innovation from Concept to Market - page 212

Table 9.3: Example of Root Causes Table 9.3: (Continued)

General Category Examples of Causes

- incorrect measurement and other metrological aspects
- incompatibility with consumables/accessories/other medical devices
- slips, laps, and mistakes

Failure modes Unexpected loss of electrical/mechanical integrity

Deterioration in function (e.g., gradual occlusion of fluid/gas path, or change
in resistance to flow, electrical conductivity) as a result of aging, wear, and
repeated use
Fatigue failure

(Source: ISO 14971:2009)

Table 9.4: Example Table of Severity Levels

L S

5 frequent 5 catastrophic

1/100 uses or Death

4 probable 4 critical

1/1000 uses or Major injury

(loss of limb, etc.):
life-threatening injury

once per week

3 occasionally 3 serious

1/10,000 uses or Minor injury requiring

treatment

once per quarter

2 remote 2 minor

1/1,100,000 uses or Minor injury NOT

requiring treatment

once per year

1 improbable 1 negligible

1/1,000,0000 uses
or

Minor irritant to
patient or end-user

once every 3-5 years

Box 7 is reserved for any description of remedial action (or comments if in the white zone).
A new level of RPN should be determined and entered into box 8. If this is insignificant all is
fine; if, however, the risk is still significant then the last next two boxes need completing. You
need to examine if the risk can be reduced any further. If it can then this needs to be described
in box 10. Simply speaking, if the residual risk is unacceptable then you must go back to the
drawing board - but if you have a good PDS this eventuality should not happen. If the risk is
significant you must assess if the residual risk is outweighed by clinical benefit and you may
need to instigate further controls.