last few weeks dealing with bench tests
as we wait for other results to come in. bench testing or performance
testing gets stuck in section 18 of the 510(k), since it is in the back
means they don't read it right? you will save yourself a lot of grief
if you read the format guidance and make sure your protocols and
reports line up nicely with their requirements, although you will need
more than what is listed in the guidance, at least a scope.
for a small company there are several challenges to bench testing, all
revolving around the number of people that have enough understanding to
run the tests. my company has three plus one consultant that can run
the majority of the tests, it is preferable to have employees sign off
on everything so the consultant is out, and one of the three has the
understanding to run the tests, but not the personality type to see it
through. that leaves the two engineers, one of which is on vacation
this week, so that leaves me for now. md&di sums up the who
should do the bench testing very well.
the first problem is the protocol, which must be signed off before the
test begins, the problem here is that no one besides the engineer
authors are likely to really understand what is going on. this means no
problems will be caught until the engineer testers try it for real.
sure, we've tested it some previously, but when everything is recorded
things change. i wrote a protocol and discovered i couldn't hold a
negative pressure i thought i could so had to change it up a bit. this
means rewriting and walking around getting signatures to get it
approved before i can start again. this is not much of a problem,
unless it is after 3:30pm and qa has gone home for the day. then i'm
forced to wait around until they come in at 9 the next day. i have
argued that by having my signature on it that the protocol has
therefore been predefined and good to go, but i haven't gained much
ground with that.
the next problem is that these tests take time, we are shooting for 24
hours of use. i rallied around testing for 26 hours but my boss vetoed
that saying 1.5 times is standard, meaning 36 hour tests and every
other day i have to come in at an awkward time (do not worry, i am
getting my revenge- see below). i am amazed my wife hasn't accused me
of cheating on her yet with the late night stops by work. the 1.5 times
the maximum limit you're shooting for is a good rule of thumb, and
appropriate here, but it doesn't work for everything, like negative
the last of my whining centers around the sample sizes that will not be
high enough to make everyone happy. with limited product and limited
resources, running a dozen 36 hour tests could take a month. unless you
are going to manufacture, sterilize, and shipping simulate a batch of
samples yourself in the next week, complaining about sample size
doesn't accomplish much. do a reasonable job and if the fda picks on it
the most likely thing that will happen is they'll ask for more testing.
i mentioned in my previous post that the deadline slipped (still not my
fault), this has given me time to come up with some additional bench
testing to put in motion. i say put in motion because i was so
confident i'd meet my part of the original 510k deadline that i planned
a two week hawaii trip starting one day before the deadline. now all
the loose ends will have to be tied up by my boss and the other
engineer, i sorta feel guilty now, but about 20 minutes after landing
it will be forgotten. i give the extra testing a 40% chance of not
being done when i get back. i have to say though that the last year has
been a blast and if you're an engineer with a good work ethic that can
tolerate the risk of working for a smaller company then go for it.
previously on failing a natural product
sterility (nps) test in a lot release using ethylene oxide (eto)
sterilization, and we finally have everything somewhat resolved, well
really a couple weeks ago we did, but i've been too busy to post. an
iso 11135 lot release requires a half cycle, then biological indicator
(bi) and nps testing which must come back sterile, then a full cycle
and further bi testing which comes back sterile. residuals and pyrogen
samples are taken from the full cycle. in the previous post i mentioned
we failed the half cycle nps testing.
after that we made our full cycle the half cycle and tested the full
cycle samples for nps and doubled the sterilization time for the rest
of the samples (this still confuses some people at the company).
unfortunately those nps samples failed as well, or more precisely one
of forty samples failed on day 7 of 14. all bi samples were negative.
after much debate and me being the ever eager middleman between
management and the sterilizer we decided to double our sterilization
time once again then proceed. however, we had to start all over with
the samples because we had used so many in testing.
while we were building more samples we looked into the nps testing. the
most notable thing was that we discovered we were using twice as many
samples as required, 40 instead of 20. 20 samples assumes you use 10
samples with aerobic media and 10 samples with anaerobic media. you can
even use 10 samples if you use the membrane method instead of using the
two types of media on the device. for us, each sample was tested
individually and had their own large media jar. we made a couple minor,
mostly for show changes to how the test was conducted.
so we built more samples and re-sterilized at a fairly ridiculous
length of time for the half cycle and twice this ridiculous length of
time for the full cycle, the length of time is so high it borders on
what the fda considers non standard sterilization. hopefully we can
lower the time some in an actual sterilization validation in the
future. oddly (imo), the sterilizer doesn't charge by time in the
chamber, so sterilizing for 1 hour costs approximately the same as
sterilizing for 5 hours.
it took much begging, but we actually managed to get these sterilized
half and full cycle in less than three weeks. we passed all the
required testing and we are finally on our way. there is another part
to our product sterilization that i'll get back to when its done.
talking to the 510(k) consultant afterwards he said sometimes companies
don't file with sterility test results. i'm not exactly sure what
they're filing with then.
since then we've been bench testing like crazy and i have been
unsuccessfully trying to delegate tests, but it seems like we don't
have any people that understand the product well enough to pass most
tests on to. we did have a dec 31 filing deadline, but its been moved.
i am happy to say that my disposables part isn't the thing that is
holding everything up despite a completely failed sterilization.