In the insulin pump system, the user has to change the needle and insulin supply at regular intervals and may also change the maximum single dose and the maximum daily dose that may be administered. Suggest three user errors that might occur and propose safety requirements that would avoid these errors resulting in an accident.

What will be an ideal response?

Possible user errors are:
1. Maximum daily dose set wrongly
2. Maximum single dose set wrongly
3. Failure to replace empty insulin reservoir
4. Insulin reservoir improperly fitted
5. Needle improperly fitted
Examples of safety requirements to avoid these errors are:
1. When the maximum dose and the maximum daily dose is changed, the user
should be asked to input the changed values twice.
2. If the maximum daily dose has already been set by the user then the new
daily dose should be no more than 1.25 and no less than 0.75 of the previous
maximum daily dose.
3. The insulin reservoir case should be designed so that it is only possible to fit
the insulin bottle the right way and the case should not close unless the
bottle is properly seated.
4. If the back pressure from the needle assembly is more than XX then the
system should shut down and issue an audible and text warning. This
allows for blocked needles as well as improperly fitted needles.