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Permalink Reply by JohnG on November 20, 2012 at 7:03pm

I'm taking Prednisone every day at 9:00am and my lunch bolus can be 25u no problem and I have never experienced channeling (insulin leaking around cannula) I use 100u a day. I have been doing this since July. The MM pump delivers a large bolus slowly so there is no leaking or burning like with some other pump brands. The cannula is also tapered and this also stops leaks.

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Permalink Reply by Nell on November 20, 2012 at 8:11pm

Thanks John. Wow! That is a fair amount, by my reckoning. I also use the MM but did not know about the tapered cannula. Never looked that closely. I will though next time I remove it. If I can find my magnifying glass.

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Permalink Reply by Frank Olsen on November 21, 2012 at 12:20am

I've always followed Dr. Bernstein's rule that more than 8u slows absorption but I have never pump bolused with that much. 6u is my largest bolus, more than that I square wave some of it. For high carb meals I'll add needle injection/s at a different locations.

I have noticed back leakage occasionally if I've left the cannula in way too many days or the site is very red and irritated. When you change a cannula one can detect that unique insulin smell if it has been leaking back. I think with a non irritated site 8u is not unreasonable.

Nell, what is a z track method?

Thanks,
Frank

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Permalink Reply by Nell on November 21, 2012 at 6:23am

Frank, I think I agree with that 'rule.' The cannula is short and injects insulin into the surrounding tissue around the clock even though small amounts. So I think I will stick with the smaller bolus amounts. I also forgot to note that since I have been type 1 since 1982 my skin has taken a lot of injections in that time. And I need it to last a few more years. My question is based on my concern that there has been no published research, that I could find, on this very practical issue. Maybe because it is practical?!

Z track injection: This is usually for intramuscular injection but I used it for the subq regardless. You place your fingers on the injection spot and then press and firmly pull your skin away from the spot. Then inject into the somewhat stretched skin spot. Remove needle and only then let the skin go. This movement causes the injection track to be a broken line instead of straight, thereby preventing seepage up the track. Do not massage skin after injection. Of course, you can't do this with a pump cannula!
This technique is mainly for caustic injectables but I used it for all injections back when I actually was in clinical nursing.

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Permalink Reply by Aeon on November 29, 2012 at 2:19pm

I think some cannula leakage on a large bolus could occur. Why not? I happened to me last week. I almost failed to notice. I had just taken a 25 unit bolus. Then, I could see liquid on top of the skin under the translucent-clear dressing (tape) I had applied. Judging from the look of it, I guess it was 2 or 3 units. But it could have been more. It seemed the site just didn't want to take the whole 1/4 of an ml volume so fast, and spit some of it back around the cannula. So the solution might be to extend it to a to square wave, or just wait a few more minutes. The site was the issue.

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Permalink Reply by Capin101 on November 30, 2012 at 8:18am

My TDD is currently 54 units. My usual plan is to eat no more than 35-40 carbs per meal. This leads to a bolus of 2.5 -4.5 units depending on many factors. Of course sometimes I go off the deep end (like thanksgiving or when I order my favorite pizza). A few weeks ago my family got a 3 meat pizza and I could not resist a third slice. 3 slices = 96 g carbs. I dosed something like 8.7 units with 6.8 normally (upfront) and 1.9 units squared over 1.5 hours. I got lucky with the bolus and the highest I tested was 141 about 2 hours PP.

I am not sure if insulin leekage/seeping is my concern for big boluses. I have two larger concerns. A huge carb load may digest differently than my normal meals (slower, faster or all at the same time). This is a variable I cannot always predict. The other issue is when the insulin is absorbed. I believe Bernstein is against large injections because they can pool under the skin. If there is a "big" pool of insulin under the skin, than is it all absorbed at once or can only the outside be absorbed and the middle is absorbed slower? Another variable that could certainly be at play for large boluses.

Occasionaly I have noted leakage issues, but I attribute this more to equipment problems like a bent cannula.

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Permalink Reply by HPNpilot on November 30, 2012 at 8:38am

My TDD is about 60 units a day (60% basal, 40% bolus).

My evening meal boluses are around 8-10 u (60-80 g of carb). I have not had any leakage or absorption problems with Omnipod. The pumps deliver the boluses far slower than a syringe or pen do and leaves time for the bolus to diffuse away from the cannula. Not saying it can't happen, but I haven't seen it personally.

My recollection is that it takes around 3 minutes for this bolus to be delivered which happens in increments of 0.05u at a time. Most people wouldn't sit with a syringe for 3 minutes slowly injecting.

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Permalink Reply by Nell on November 30, 2012 at 12:44pm

HPN, you can inject a lot of insulin with a syringe and just use common sense slow inject. But then you leave that site and don't use it again for days or weeks. Contrary to the pump insertion which stays in the same place for a few days. I think that makes a difference in absorption for larger boluses. "I think" but I don't know. But so far a number of folks have indicated that larger boluses can leak back out--for pumpers.

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