Page 125 - Safety Risk Management for Medical Devices

104 Safety Risk Management for Medical Devices

As in other FMEAs, PFMEA is a team activity. A suggested PFMEA team compo-
sition is presented below:
• Manufacturing engineering
• Manufacturing technicians
• Systems engineering
• Quality
• Clinical/Medical
• Risk management

12.7.1 PFMEA workflow
In the following sections the workflow for PFMEA is described. The workflow corre-
sponds to the template that is provided in Appendix B—Templates.

12.7.1.1 Set scope
Identify the process that will be the subject of analysis. This defines the boundary of
analysis. Does your process include receiving inspection? Does it include warehousing
after the completion of manufacturing? Does it include shipping? Be very clear on
what is included in the scope of analysis.

12.7.1.2 Identify primary and secondary functions
Identify the primary and secondary functions of the product of the process. Primary
functions are those that achieve the main mission of the product of the process under
analysis. In other words, primary functions are why the product is purchased. All
other functions are secondary. For example, a pacemaker produces stimulation pulses
to the heart, but also logs device faults. Both are functions, but producing pacing
pulses is the primary function of the device, and fault logging is a secondary function.
The reason for this classification is that determination of the severity ratings of
Failure Modes which do not have a safety impact, is based on the impact of the
Failure Mode on the functionality of the product.

12.7.1.3 Process Flow Diagram
Process Flow Diagrams (PFDs) are a graphical way of describing a process, its constitu-
ent tasks, and their sequence. A PFD helps with the brainstorming and communication
of the process design. The PFMEA process needs a complete list of tasks that comprise
the process under analysis. The level of detail can be decided by the team. Including
more detail takes time, but it reduces the probability of missing Failure Modes.
Manufacturing engineering should be able to produce the PFD. A good way to go
about creating the PFD is to first log the major tasks of the process. Then add the
detailed tasks, and the steps necessary to realize each task. Next, have a walk through