How I beat the bubbles

I’ve been using the tslim since February. By far, my biggest frustration has been with the loading process and the bubbles that I’d continue to find in my tubing for the next three days. Tandem support told me to make sure that I was using room temp insulin and that I kept the pump upright, which I was already doing and didn’t really solve anything. After a lot of profanity, I’ve landed on the process below which has kept me pretty bubble free for the past three site changes. The bubbles that I am most concerned about are the big bubbles that can get caught in the luer lock - Tandem support told me that these big ones (bigger than a pinhead) HAVE to be broken up and moved out of the connector because they are affecting basal delivery at that size.

Ok, so here’s what I do:

  1. Get all the various things together.
  2. Put the needle on the syringe and stick it in the new cartridge (not yet installed). Pull plunger back until you feel resistance. Then remove syringe from cartridge, keeping pressure on the plunger to not allow air back in. I usually pull out about 50 units of air from the cartridge.
  3. Start the cartridge load process on pump. Remove old cartridge and install new one.
  4. Draw fresh insulin into syringe, removing air bubbles as you go and knocking with tooth brush to get rid of bubbles
  5. Stick syringe into old cartridge and pull plunger to get out the 50 units of leftover insulin in there (even though the pump said less than 20). Pull plunger until you feel resistance or until you start seeing air bubbles. Flick out any bubbles from syringe.
  6. Follow the rest of the load process as stated.

The only complication that I’ve noticed with this process is that, almost regardless of the amount of insulin that I load (usually 180-200 units), will register as 160 units. I learned at the beginning of my tslim journey to never trust the unit gauge, so I’m ok with that. The delivery mechanism is the part of the pump that actually measures anything, and I don’t believe I’m affecting that.

So that has helped restore my sanity and revive my love affair with the tslim a little. If anyone thinks I’m messing something up, I’d love to know! Happy to answer any questions, too.

The part I don't understand is "remove syringe from cartridge, keeping pressure on the plunger not to allow air back in." If you've stuck the needle in the new cartridge and pulled the plunger back, there should be air in the syringe, so how can you not allow air back in? Am I missing a step?

Well, when you’re move the air from the cartridge, you create a vacuum in the cartridge. If you let go of the plunger on the syringe before you pull it, the vacuum in the cartridge will try to suck some of that air in the syringe back into the cartridge. So you just keep slightly pulling on the plunger as you take the syringe out of the cartridge, which then reseals the cartridge, not letting any new air in.

I pull air out of the cartridge before I install it to the pump, too. I also manually prime the tubing and only use the pump to prime the pigtail, then I manually attach the tubing to the pigtail. It's cut down on a lot of waste and gotten rid of pretty much all problems of having a tiny bubble in the luer lock after a fill.

you could put about 20 units of insulin in the syringe and when you have the new cartridge installed and the pump says its prepared the cartridge and is ready for you to fill it.

THEN you could use the syringe to pull air from the cartridge - having 30 or so units in the syringe helps you visualize the bubbles as they come out AND keeps air from going back in

this system works for me and I have NO issues with bubbles

Have you tried flicking out the bubbles in the connector and into the tubing during the prime? Usually after I get those out, I don't get any more.

Is it really necessary to use a tooth brush to know the air bubbles out? Is that essential? What if I don't have a toothbrush in the kitchen? :)

Has anyone tried reusing the tubing so that it doesn't have to be primed with 20 or so units? Results?

That's what I do. Right around 9u while priming that big bubble is ready to go from the luer into the tube. I sometimes have a problem lining it up to start up the tube.

I use my finger and flick the syringe, but this can really hurt your finger if you do it too hard or too many times. This is where the toothbrush is a good idea.

That's a good question. I can understand replacement of the set, but how many times could the tubing be reused.

Yes. You can do it once, but if you try to use it too many times, it tends to get occlusions, and then it's a pain, and you have to use a new one. So my rule, after multiple tries at various ways to get around the system (and save money) is reuse once; after that, it's not worth it.

Ok, so I have been pumping for 3.5 weeks now with the t:slim. Despite my fondness for technology and the pump I have tried every suggestion found by google for getting the air out and a few more I have discovered on my own. Of course, I have also done the way taught by the trainer and no matter what I try, even if I think I have all the air out no more than every 6 to 10 hours when I check the lure lock I have more bubbles.
I also now tighten the lure lock or at least check it to make sure it didn’t work it’s way loose during every bolus.

Any other suggestions would be appreciated.

Things I have done are:
Using room temp insulin, as well as cartridge and other needed supplies
Tapping the cartridge during priming
Pre-filling the tube and connecting once the male part has a bubble on it after tapping air out of the carriage
Slow, very slow insulin extraction and filling the cartilage
Pump is alway standing up on side during fill process
Pump is laid on back during preparing the cartridge
Making sure all air is out of the syringe
Using insulin syringes to fill

I've tried almost everything too but still have issues with the luer lock bubble. I can prime it out in the beginning but it always reappears an hour or two later. I don't THINK it's affected my BG's but I can't ever be certain and don't like that extra variable in the mix.

I too have a lot of bubbles in the the pump and have done the same standard remedies with room temperature insulin and flicking and all. The pigtail will have a bubble that I can get out but still another bubble will form at some point. I am curious how you are manually priming the tube Suz? Has anyone noticed that when the pump says it is done installing the cartridge it does not always say 100 percent complete but some number less then 100 percent? That makes me think the pump is not pushing all of the air out.

The calculation on the resivore change is just the software not hitting %100, the piston rod senses the pressure when pulling the air out, and sometimes this happens before the bar hit 100. It’s like the download time that Your web browser estimates, it’s just an estimate and sometimes the download is faster or takes longer.

As for the manual prime, what suz was referring to is after filling the cartridge you would draw a little more insulin, recap the needle (by the way it’s not recomended to ever recap any needle) and remove the needle from the syring. The syring is a lure loc just like the connection on your infusion. Now you can hook the syring to the infusion and manually push insulin threw the tubing. Disconnect the syringe then start the fill on the pump. Wait for a drop to appear on the lure loc connection from the pump, then join the infusion and pump together. If done quick enough no air is caught when you screw the infusion on. Drops will happen as usual and you can stop the filling at 10 units. The pump will not let you fill less than 10 after a new cartridge change. Suz please correct me if you are doing something different.

Side note, if you change the cartridge every three days some people use the syring to extract the left over insulin on the old cartridge for the manual priming. This would only work if you use humalog that is good for 7 days once drawn from the vial, or novolog that is good for 6 days once drawn from the vial. I would personally not do this on hot summer days if the insulin temperature ever reached above 98.6°f (31°c).

How do you manually prime the tubing?

Thank you Lizzie for the information. I did come up with another way that also uses your idea of tapping the reservoir and wanted to share it.

Again, I would like to thank Lizzie for the tapping idea, it got me thinking to want to understand more about the pump and to take apart one of the cartridges to see where the air would be trapped in the best way to get it out and with a hours of reverse engineering the cartridge I was able to come up with this method that has worked the best for me so far.

You can get the link to my video in this thread.

Hi - new here -- just want to offer my 2 cents. I never seem to have probs with bubbles. Prime your need with air a few times - then plunge a full needle of air into your vial. I was taught when drawing the insulin from the vial, draw a bit more than you need. When the need is full/what you need, hold it by the end of the part you draw back and flick the areas that have bubbles up top (don't hold fat part of the need when flicking) -- this seems to help pop bubbles really good. flick all over and squirt out any little bubbles in the tip. Works every time for me.
Good luck.