I've discussed this problem with my endo who is T1 and uses a Medtronic pump. He's not aware of this pattern of highs with site changes in his own experience. One plausible explanation is that the site trauma with cannula insertion is less with the Omnipod, such that it requires more initial insulin in a subcutaneous depot to start getting diffusion into the blood system and reaching a "steady state" for basal delivery. Kids with much smaller basals and boluses would exhibit more of a problem. Insulin has a molecular weight of about 35,000 Da, which is way larger than salt ions, oxygen, glucose, water, etc. that diffuse much more readily. So it may reach the blood system in a timely fashion only if there is sufficient trauma, AND/OR there is considerable positive pressure buildup of insulin after a site change.
I wonder if standard pump users report this kind of problem? If so, it may be associated with certain types of infusions sets having gentler insertion, smaller diameter, shorter length, teflon not steel.
I agree with JBowler. I see the same problem in areas that I never used in 35 yrs of MDI. It is not from site overuse in our cases, but that can also a factor.
I believe JasonN has the answer; it's an issue with pod priming. See his post below and the picture I attached from my last pod which shows the air bubble.
That air bubble can easily get to the outlet port and result in a few units of air replacing the humalog.
We do the "pinch up" but we DO NOT push down, he is "extremely" lean & tall, Almost 5 ft. and just turned 8 in Dec., and when we pushed down while pinching up, He had so many occlusions. Now we only pinch up and "Thankfully" that has stopped the occlusions. We will try the pre/post bolus and see what happens. THANKS!
Thanks for the picture, as soon as it beeps twice you then pick-up with the right corner (of the fill port) pointed up? Do you hold this way until the priming is completed? I hope this works. He has only been T1 for 1 year and 26 days. 4 MDI for 8 months and then Omni-Pod. He WILL NOT go to another pump, he says he will NOT have tubes hanging from him. He loves this pump, so do we, it has been a life changer, literally, but the last change, which was Monday he went from 89 pre-change, to 390 two hours later. (uggggghhhh) Thanks!!!
I just tried this, after experimenting with an opened pod to see how to hold it to get any air-bubble next to the output port. It seemed to have the opposite effect to that desired:
23:09 BG 206 mg/dl 23:09 bolus 1.35IU (the old pod; that should have fixed the high BG)
23:16 Pod deactivated
23:19 Pod activated (basal .5 IU/hour)
01:02 BG 218 mg/dl (it woke me up)
01:02 bolus 1.20IU (that should have fixed it, again)
04:36 BG 200 mg/dl (woken up again)
04:36 bolus 1.50IU
07:48 BG 149 mg/dl
So it's finally getting back in line, and during the night I felt like I wasn't getting any basal dose (tingling in the my arms and legs). Over 8 hours I should have got 4IU of insulin and the original 1.35 IU should have corrected the high I had at the start. (That was probably failing to account for the sugar in two glasses of sweetish red wine; no carb information on wine bottles in the US!) Instead I had to bolus a total of 4IU just to stay steady.
This suggests I only got half the insulin I asked for over the night.
The previous pod (the one I had primed the "wrong" way) actually had less air in it that the first one I opened, but that's only after I'd used it three days so it really doesn't prove much.
OK, I've cracked open 4 pods after use and consistently see an estimated 30-50 uL of air as a single bubble remaining. I also tried priming with the exit port corner up, tapping the pod to disodge bubbles before the priming started and it did not seem to help.
What this means is that the bubble must compress to the point where it equalizes with the backpressure of the infusion site. If the site has a backpressure of say just one atmosphere (and it is probably considerably more), then for a 50 uL bubble you would need to bolus + basal 2.5 U (1U=10uL) just to equilibrate with the site backpressure before any insulin started to infuse into the site. Barry Ginsberg has a paper touching on this problem with inuslin pens : The Kinetics of Insulin Administration by Insulin Pens
I thinks this is why the "high after pod change" is so widely reported in kids: they are so low-dose that accumulating enough intial bolus and basal to overcome the pressure of the bubble takes a long time.
One thing Omnipod could do is redesign the exit port so that it had a funnel shape that could catch the bubble when that corner is upright during priming. I took the insulin chamber apart and the exit hole is quite small and the surface around it flat.
In the meantime I think many people have hit upon the solution by doing a "compression bolus" of 0.5-several units after changing a pod. One could start doing this by starting at say 0.5 U after your next pod change, and if you still go high, try 1.0 U the next time, etc. And be aware of the occasional small bubble that might result in a too large compression bolus, so test early and often!
hi mark! your comments made me smile, you must be an engineer, may be you could work for insulet and improve the product! honestly your comments make sense but i would never of put them so intellegently, my son wants to be an engineer someday! time will tell he is only 13 but i am impressed with his goals. hope you had a good easter! amy
wow! we experimented, starting at .5 units, and have found 1.5 units is just about right!! You should call support with your findings, I think if omnipod would acknowledge this and create process for implementation for finding the right amount, it would be really helpful... but then that dang fda, they will be watching, so I understand that could be a concern...
We just started the OmniPod on our 4 year old son and have had the exact same issues. We were seeing blood sugars over 400 in the hours after changing the pod. We would pump the corrections and see no change. Where could the insulin possibly be going? Have had to use injections to control the highs as well as get keytones to dissipate. We are really looking for answers. Has anyone contacted Insulet to ask about these issues? If it is the pump, why isn't it error messaging? I really feel (if the pods actually work the way they are supposed to) that this is the right choice for us. I really have no desire to try a pump with tubing. Our trouble has been with the same site (on side of leg) and it may just be that there is not enough actual fatty tissue? We aren't ready to give up yet but have felt quite disouraged more than a few times since starting.
Hi Judy- many of us are seeing the same thing. Please read this response to get an idea of what the problem very well might be: High after Pod change?
Until Insulet acknowledges and fixes the problem you will have to be aggressive in minimizing this problem. In my recent experience I find that a minimum of 3U bolus immediately after a pod change seems to abolish the problem. If you try this, of course, do it during a period where you can test frequently for several hours. The problem is that we don't know how reproducible the correction is, but in my experience it has been quite stable. If you have CGM then you can feel safer about the issue.
Your point about too little subcutaneous fat is good: muscle might have higher back pressure than adipose tissue, so the problem may be more pronounced.
hi judy i feel your frustration we were there but have had a much better stretch the last few months with doing the post pod change bolus, it seems to be a priming issue? the higher jacobs bs at the time the more we give see my previous post, it works! also maybe try to not have him eat an hour or two post pod change best wishes i cant tell you how much of a difference this has made for our overall omnipod satisfaction. best of luck! amy
I think we have a system pretty well down. We do a .4 to .5 bolus before the change, then deactivate immediately after. Get the new pod ready, filling the reservoir with the fill hole up, then let the pump prime while the fill hole is still in the upward position (tilted in the plastic container it came in). When we do the canula insertion, we pinch the skin to ensure that it goes into a good "fatty area". After a successful insertion, we give her a .5 bolus again.
That seems to work best for us. I think it's pretty well established that there's a priming issue on these pumps. (In my opinion) you just have to "get it going" in order for it to start delivering the basil properly.
Of course, while we were getting this system established, we were doing the pod changes around 4:00 in the afternoon so we could monitor her. We were too aggressive a few times and had to catch her before she went too low, so keep that in mind.
Our daughter is just over 2, so she's not taking much insulin. I think that's the main reason for her highs after the pod change, since not getting .2/hr for 2 hours will shoot her up into the 400's pretty easily.
I can't wait for the NEW pods that have the canula a different color so we can SEE it in the window. What's the point of having a clear tube behind a window that you can't see?
