[IP] "Bubble-less" Cartridges
Since I haven't posted this in about a year:
I believe that a difference in pressures in the vial is what causes
bubbles to be introduced into solution when the vortex of insulin
rushes down the needle. To help equalize these pressures, start
with a standard syringe from which you have removed the plunger.
Insert this into the vial to allow air to either enter or exit the
vial, equalizing pressures. Remove the syringe and set aside
(carefully, keep it sterile!). Prime the cartridge that you are
filling to lubricate it, then expel all the air that you can.
Insert the cartridge needle and invert the vial and draw enough
(10-30 units) insulin to be able to free the bubble from the plunger
tip. Expel that bubble back into the vial and draw just a few units
into the cartridge, at this point the pressure should be going
negative in the vial. Insert your plungerless syringe and allow air
to be drawn into the vial. Begin drawing your insulin slowly, making
sure to keep the two syringe needles separate from each other. You
don't want to draw air off of the equalizing syringe. After you have
filled your cartridge, remove the equalizing syringe, then the
cartridge from the vial.
Having drawn your insulin in a "pressure-free" environment, you may
discover that fewer bubbles develop out of the insulin solution even
after time. It has worked for me for the past 6 years.
Hopefully, my directions are explicit enough, but if you have a
question, please write to mailto:email @ redacted and I will be
happy to answer.
Let us now give credit where credit is due. I believe that I first
heard of this technique from a page that John Neale of IP-UK had
posted. Many thanks to John and all that he has done for IP and all
it's members. This is the true Spirit of IP! ;>)
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