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Reverse-engineering the Omnipod Bubble

Discussion in 'Parents of Children with Type 1' started by Darryl, Feb 14, 2010.

  1. evinsmom

    evinsmom Approved members

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    Scott,

    I didn't specifically ask about highs post-pod change and priming orientation. To be honest, I basically blew off what the guy was saying about priming. It was the first I had heard it. It was also brought up in that series of questions that just drive me crazy - "Did you fill the pod with insulin?", "Did you get two beeps?", "Did you get the priming message?", "Did it beep after priming?" Are you serious?!? And they asked me these questions 10 times - one for each failed pod.

    We also struggle with highs post-pod change and have done many of the tricks mentioned here - including priming while vertical. I didn't see a difference when we primed that way - my son was still high after. What seems to work best of us is to give a "bump" of .75 units after a change before a meal or big snack (not a little snack).

    I think I'll have to do the experiment mentioned in the thread about filling the cannula on the Omnipod ? maybe priming one horizontal and one vertical. That would be very interesting to see.
     
  2. Darryl

    Darryl Approved members

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    As the rep said, this is the reason they recommend priming the pod with it lying inside the container - it keeps the pod stable so it doesn't tip over or fall of the table while priming. A jolt to the pod while priming could cause an abort if the presure sensor was tripped.

    The orientation, per se, does not seem to matter with regard to whether the air is forced out of the chamber.
     
  3. Darryl

    Darryl Approved members

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    Did you try leaving the old pod on for an hour after the new one is installed? We have found this is necessary to prevent newly delivered insulin at the old site from leaking out before it is absorbed.
     
  4. vettechmomof2

    vettechmomof2 Approved members

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    CS has also told this to me before, their reasoning was that if the pod got tilted a bit while inserting insulin you could actually alter some of the tubing inside and they could disengage causing failure.
    So they recommend keeping it in the container for filling.
    I have only heard that once from CS.
     
  5. Darryl

    Darryl Approved members

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    ** Update **

    Swellman - you were right. The plunger does start in the fully extended position, and injecting the insulin pushes it back.

    I found a way to see pretty well inside the pod during priming using a light scope. So I filled it, and watched the insulin push the plunger backwards. Initially the spiral gear on the plunger is not engaged, which is how it can be pushed back easily. The gear appears to engage during the priming process.

    A couple of things I noticed and can say for sure now:

    1) A small bubble did form in the chamber when I injected the insulin, and was still there after the priming. Judging by the size of the bubble, it was around 1u or 2u (size of a small drop of insulin). The priming did not compress, expel, or move this bubble from where it was resting on the side of the chamber. After priming, I gave the pod a good snap with my finger and the bubble floated away somewhere else.

    2) The priming does fill the cannula. It clicks more than enough times. I could see insulin fill beneath the plug after 12 clicks, and it kept clicking after that, about another 10 times.

    So the conclusion remains that air can indeed enter the chamber, it is not expelled by priming, but if the bubble is small, it is unlikely to be positioned exactly at the outlet unless the cannula is pointing straight down at exactly the necessary angle.

    I would recommend being very careful to expel all air from the syringe before filling a pod, but am not to worried about bubbles actually reaching the cannula. The way we get air out of the syringe: After filling it, we hold it needle pointing down, then tap up until all bubbles rise to the black stopper. Then when filling the pod, we stop the syringe before the stopper reaches the bottom. This is easier for us than trying to get bubbles out with the needle pointing up.
     
  6. Melissata

    Melissata Approved members

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    That is the method that I use as well to make certain that no air gets injected. It is easier than trying to get the air out of the needle. Just leave it inside the cartridge!
     

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