Design Realization/Detailed Design - Medical Device Design: Innovation from Concept to Market - page 190

Table 8.10: 6 σ Seven Wastes Applied to DFS

Waste Description/Question

1. Waste of overproduction

l

How many washes are required for acceptable bio-burden levels?

l

What level of sterilization is required to ensure sterility?

2. Waste of waiting

l

Are blind holes, etc. included that will require specific tests to be
undertaken?

3. Waste of transporting

l

What facilities do the end-users normally have on site?

l

Have we designed in a system that requires specialist centers to
sterilize and hence involves transportation?

4. Waste of inappropriate processing

l

Are the sterilization protocols standard?

5. Waste of unnecessary inventory

l

Do the end-users need special tools to clean and sterilize your
device?

6. Waste of unnecessary motion

l

Packing devices into standard trays?

l

Packing and unpacking by central cleaning/sterilization services
(CSD)?

7. Waste of defects

l

Can CSD lose components?

l

Is the device sterilizable by “normal” CSD units?

“New” Waste
7(b) Waste of untapped human
potential

l

Have you sought advice from those who may understand the usual
processes in situ?

restricted to holes; bio-burdens can get trapped in machining marks, poorly assembled
joints, and gaps.

Many cleaning/washing regimes are very harsh (Ph13/14 is common). They can destroy
aluminum components at a whim. Can your device survive the cleaning/washing process?
This part of DFS is very easy - talk to the people who actually do the cleaning/washing.

Questions you should ask are:

l

How will my device be sterilized? What affect does this have on my device?

l

Will it be reusable?

l

Will washing/cleaning affect my device or its components?

l

Can my device be washed properly? Are there any blind holes? Are there any long
cannula? Is there any chance of bio-burden collecting?

l

Are there cracks/joints that may cause bio-burden issues?

As with previous sections, spending time on this aspect will help with the risk analysis
required later.

8.7.5 Design for Environment/Sustainability (DFE)
If you look in any design handbook before about 2000 you will find a cursory glance at
this topic, if anything at all. It is a truism that before we became aware of our impact on the