Bubbles in insulin reservoir


#1

I use the MiniMed Quick-set system and no matter how careful I am, I get air bubbles in the reservoir. Most are quite small but occasionally a large one gets into the tubing. This, of course, plays havoc with my blood sugar control if I don’t catch it in time.


#2

Well, you’ve hit on a hobbyhorse topic of mine. Those dratted bubbles caused me no end of aggravation and frustration when I switched from MDI to a pump (Minimed) 2 1/2 years ago, to the point that I was about ready to give up and go back to MDI. I started out 30+ yrs ago on R/NPH and thwacking syringes to get bubbles out was something I thought I’d never have to do again after switching to those handy Lantus and Novolg pens. Ah well.

A couple of things: I was told that letting the insulin warm up for 20 minutes keeps it from generating so many bubbles when you pull it into the reservoir. Last time I mentioned that here it seemed like no one else had ever heard of it and never had any problems… but it’s worth trying. Over time I got better at it, but it’s a perennial problem. Some people say using a pen to do the thwacking, instead of a finger, also can help dislodge the stubborn little things. Didn’t seem particularly more effective when I tried it but you might have better luck.

I’ve actually solved this problem for myself in a different way. This may not be practical for others because the way I arrived at it is kind of singular, but maybe worth mentioning anyway.

It turns out that you can actually get a prescription for just the cartridges that are used by insulin pens. This is what the late lamented Asante Snap was using, and one of the main reasons I switched to a Snap last winter was not having to deal with bubble-thwacking. Asante having imploded, I went back to my Minimed, but someone on TUD said he was still using his Snap Humalog cartridges to fill his Medtronic reservoirs, essentially eliminating the bubble problem. Since I still had a bunch of cartridges left I gave it a try. It’s similar to pulling the insulin from a vial, except the rubber cap is smaller and a bit more resistant to being punctured by the reservoir needle. But the cartridge is designed to dispense insulin from a plunger at the other end, so it automatically compensates for the volume of the insulin you’re pulling out of it. You don’t have to push any air into it: the stopper at the back of the cartridge just slides along as it empties. You do get a single bubble when you first start to draw the insulin in because there’s a teeny bit of air in the needle itself, but a single good thwack and push of the plunger gets rid of it. This has been working so well for me that I’ve actually kept my cartridge prescription going. It would probably be a bit involved to switch to this method from zero, but I’m guessing you and I are not the only ones driven crazy by this problem so I thought it was at least worth getting it out there…


#3

I do a bubble check every day and have always done so. All manner of following directions does not eliminate the occasional air bubble trubble. And for sure they can play havoc when they are more than a tiny bubble. I primed one air bubble line out of the connect and it took 1.5 units to get through and start dripping insulin. That’s hours of basal for me! This is why I check every single day.

I will mention that today’s sets allow us to prime them out so that is a great improvement and makes it easy to manage those trubblesome bubbles. We used to have to guestimate and then bolus the air through the site when a bubble was discovered.


#4

I will mention that today’s sets allow us to prime them out so that is a
great improvement and makes it easy to manage those trubblesome
bubbles. We used to have to guestimate and then bolus the air through
the site when a bubble was discovered.

I’m still guestimating the amount of bolus to push out the air bubble. I use the same system that I use to fill the cannula. Do you have another way to prime them out?


#5

I have the bubble problem sometimes myself and had heard that they’re less likely if you let the vial warm up before transferring to the reservoir. I worry that if I do this it will reduce the usable life of the insulin in the vial. Let me explain, I’ve been told that I can leave the vial at room temperature for up to 28 days, after that it is no longer viable. I don’t do this because I end up throwing away about 1/4 of the vial as I don’t use it fast enough. But if I let it warm up for 20 minutes and then cool it back down for 3 days does it have the same effect as leaving it at room temp the whole time? If not, how long can I leave it at room temp before it begins to change and does cooling it back down reverse the effects or just stop them?
The other thing I’ve tried with limited success is transferring the insulin while it’s cold but then allowing the reservoir to warm up before priming the tubing. Has anyone else tried this method? Any tips on how to make it more effective?

BTW: I have a MiniMed pump.


#6

i really wish I had the time and equipment to make a video to demonstrate how I get no bubbles in my set tubing all the way through the 2-4 days that I wear each set. It took me years to figure out how to do it and I can’t convey the method with mere words, but it IS easy to avoid bubbles ONCE YOU KNOW HOW.


#7

[quote=“Goldfish, post:4, topic:47132, full:true”]
I’m still guestimating the amount of bolus to push out the air bubble. I use the same system that I use to fill the cannula. Do you have another way to prime them out?
[/quote]That is the way I use, too. Just disconnet, fill the cannula, reconnect…wah lah :slight_smile:


#8

No smartphone @phoenixbound? I’d love to see how you do it!


#9

I have been whacking the vials, too, and have been warming them since I got that advice from the Medtronic help line. I have kept getting the “Insulin flow blocked” message so often I was beginning to think about abandoning the pump. It’s not great when this happens at a formal dinner when you are 200km from home, or eating a quarter pounder at a railway station, as happened to me last Sunday.

So, earlier this week I saw a video which claimed that you can eliminate bubbles by evacuating the vial, by drawing air out of the vial rather than putting air in. I tried this with the last refill, and it seems to have worked. I was unable to coax a bubble out of hiding after filling the rez, andhaven’t had the ‘flow blocked’ message from it. If I find that video again, I will post the link here.


#10

And here it is!

The advice I got from Medtronic was to warm the insulin. Never anything about degassing.


#11

More discussion about the "degassing concept’ found in that video can be found in this thread.