I fill my daughter's insulin pump cartridge with about 60 units and I am absolutely positive there are no air bubbles in the cartridge. I put the cartridge in the pump keeping the luer lock end pointing up so no air can enter and I prime the tubing with the cartridge upright.
Every time we go to change her cartridge, usually with about 8-10 units left, there are several air bubbles in that remaining insulin. I don't understand how they are getting in. I have to wonder if sometimes she doesn't get the correct dose because some air gets into the line.
I fill my pump the same way like you are doing and hit it with a pen. I believe the air bubbles are gone, but they are always there when I change my site. Let's just say my A1C has gone up to the high 6's/ 7.0 since being on the pump vs. when I was on shots I was in the low 6's.
air bubbles are common, and unless there is a huge one in there, they are just annoying.
There is gas dissolved in the liquid, you'd never know until you trap it inside something, like a reservior. you can tap until the cows come home, you can't get rid of the dissolved gasses. they are most reduced when you let the insulin stay at room temperature for at least a week. refrigerated insulin can hold more dissolved gasses than room temperature insulin (this is why warm soda is more fizzy than cold soda).
it's also pretty common for a1c to go up when you first start pumping.
I always get air bubbles in the cartridge even when I bang it with a pen and feel like I've gotten all the bubbles out. My husband has the same problem also. What I've been doing is after a day or so I check the cartridge. If there are a lot of bubbles I will actually try to accumulate them in the top so that I can get them out. I use the Medtronic MiniMed pump so when I find that there are a lot of air bubbles I will try to get the air bubbles out and refill the space with insulin. First I disconnect the pump from me and take the cartridge out of the pump. I'll then usually mark on the cartridge where the insulin level is. I'll then accumulate the air bubbles at the top and then reconnect the needle so that I can get the air bubbles out and refill the space with insulin. I will then reinsert the cartridge in the pump and then reconnect the pump to me. This way if I've overfilled the space on insulin I don't get an overload of insulin in me. :) Overall, my blood sugar control hasn't been affected too much by it but there are a few times that I've run high and I suspect it is because I didn't get the correct dosage. I've found that by checking every few days and going through this process that it has definitely helped.
I think a few air bubbles are pretty common. My endo said as long as there's no huge ones, I would probably be fine. I still remember the first time I ever got pump training, the educator used the Sof-Serter (insertion device for those who don't use MiniMed) to tap the side of the cartridge and make the air bubbles float to top to be released back into the insulin bottle. She called it a bubble-whacker and the name stuck. I usually get weird looks when I say "bubble whacker".
We have only seen bubbles 1 or 2 times in 10 mos of pumping with my son. He has an Animas Ping and uses inset 30 infusion sets.
I am wondering if - taking the cartridge out of the pump causes bubbles to enter as it could pull the plunger part out slightly.
How often are you disconnecting from your site? I wonder about that sometimes if there is a possibility of getting air into the connector on the site and then introducing air into the tubing that way.
I'm a biomedical engineer, so I wonder about all these things in the way the pump works. (Probably way too much). Also, I would encourage you to call your pump supplier and let them know esp. if this occurs alot - they can't fix problems on future pumps/infusion sets if they don't get reported.
We also have the Animas Ping and bubbles haven't been a problem. As long as I push the plunger hard against the top and draw it slowly, I rarely get bubbles. If I do, I push the insulin back up, make sure the needle isn't close to the surface of the insulin (sometimes I turn it so it's facing away from the side, that seems to work better), and try again. I usually get it perfect on the second try.
I get bubbles every time. But I don't consider it a 'problem.' 'Champagne bubbles' in the tubing are generally harmless and quite common.
Think of it this way: one unit of insulin fills approximately 1.5" of tubing. That should give you some idea if you should worry when seeing the bubbles in the tubing. For me, my usual basal rate is 0.5u/hour. So if I see a bubble that is approx. 3/4" long, I know I've missed an hour's worth of insulin.