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Mariel's Mom

Bent Cannula - Why do Cannulas go bad?

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Mariel's Mom

Ok, So today was the first time we had to change Mariel's infusion site. And yes as Murphy would have it - all evidence suggests I somehow had or created a bad insertion.

 

2 hours after her dinner bolus she was registering "HI" on the meter. I bolused a correction (per Doctor's instructions) - 1 hour later the meter is still greeting me with "HI"!

 

Dr said it looked like a bad site so we changed it and gave a correction bolus. I was never so happy to see 455 on the meter 25 min later. We looked at the cannula and it looked well, just askew - not bent. So my questions are:

 

1. What does a bent cannula look like - how bent must it be to impede insulin delivery. Mine looked like a 80 degree angle vs a 90 degree angle-straight in.

 

2. Is the site bad at the insertion - period - or are there situations that a good site can go bad after a few minutes (Mariel's sugars were going down after the initial site change but it could have been the 1 unit I gave her at 3:00 for a 20 g. snack so maybe it was just bad from the start

 

3. Are there insertion technique errors that can create a bent cannula that I can fix if I knew about them or is it just a bad set. (Did I cause the bad set by how I held it - pressed the little launch area - (BTW we use Insets). Help -

 

This was really scary and it is going to be a long night.

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Cyborg

I've been wondering the same myself. I also use the Insets and have not had a single bent cannula. At first, I was cautious to not sleep on a site, etc., but know if it doesn't hurt, I just get comfortable. So how do these cannulas get bent? I just got a box of 6mm to try, rather than the 9mm. Are these going to be more prone to bending?

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psilocybin

i havent had a bent canula either and i use the comfort shorts...i picked these due to the price...insets are expensive along with most other sets...140 bucks of 10 sets of comforts is a good price and i can afford that....

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poodlebone

Some reasons a cannula, especially one that goes straight in at 90 degrees, can bend is there's not enough fat in the area being inserted, or you hit a music. I started having nothing but trouble using Quick-Sets late last year and finally gave up. Sometimes when I pulled a bad one out it looked okay, or just slightly bent, but I guess it could have straightened out more as I withdrew it.

 

I have had some sets that worked fine for a day or two, and then suddenly seemed to go bad. I guess if you're extremely active and the site is in an area that maybe moves a lot (through bending, twisting the body somehow) it could get bent or dislodged while it's inserted.

 

Minimed had sent me some of the 6mm Quick-Sets to try and I also got bent cannulas with those and finally switched to Silhouettes, which are longer and go in at an angle. I have not had a single bent cannula with them yet.

 

Also, make sure that all fo the connections are tight too, since that can also cause high readings if something is loose.

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Mariel's Mom
I've been wondering the same myself. I also use the Insets and have not had a single bent cannula. At first, I was cautious to not sleep on a site, etc., but know if it doesn't hurt, I just get comfortable. So how do these cannulas get bent? I just got a box of 6mm to try, rather than the 9mm. Are these going to be more prone to bending?

 

 

So have you ever had an instance where it just wasn't working for some reason and you had to replace it and suddenly it worked?

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Cyborg
So have you ever had an instance where it just wasn't working for some reason and you had to replace it and suddenly it worked?

 

One time when I first started pumping I wasn't sure if there was a problem, but I did end up changing out and dosing with a syringe. After a new infusion set, all was ok. I sort of adopted a philosophy of, "when it doubt, take it out". If diet and all other factors are normal, but sugars are running high, it doesn't hurt to switch out a set. I'd even ask the medical supply company for a free box since you are a new to pumping. You might be surprised what they are willing to give out to keep your business.

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JediSkipdogg

Bent canulas can happen for a number of reasons and it's almost impossible to predict. A bent canula usually comes from inserting the canula and hitting something harder than fat, whether that is muscle or scar tissue it's unknown (since you can't see inside your body while inserting.) They can also come from pushing on it after it has been inserted. I'm not saying don't push on it, but you have to remember the needle is no longer there to assist in the inserting. Therefore you have a soft pliable plasting pushing on a hard fat (harder than the plastic) and that can cause it to bend. Some people choose not to lay on insertion sites. But in my 4 years of pumping I lay on them quite a bit. And have only seen a handful of bent canulas and many which actually still work and I don't see them bent till my 72 hours is up.

 

What does a bent canula look like? Take an old canula sometime that isn't bend and simply bend the end about 1/16" down in half. That's a bent canula. It would look like the end of the tube was crushed and not straight. It usually, 99%+ of the time will be at the very very tip of the canula.

 

How can you tell if it's a bent canula or not? It's really hard to tell a bent canula from a bad insertion site. There are many reasons each one may occur and the only obvious one is an unexpected rise in BGs that you can't seem to get down. You can have both immediately after putting a new insertion site in. That's why they recommend not changing infusion sets 3 hours prior to bed.

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David

I think you've gotten some good answers about bent cannulas. The only thing that I'd add is that there are some infusion sets that don't have bent cannula problems, those that use metal needles. These include Minimed's Polyfin, Unomedical's Basic and Contact, and Disetronic's Rapid. While they're not for everyone (those sensitive to metals), they're not as bad as they sound. Actually, I've found them to work very well.

 

David

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JediSkipdogg
I think you've gotten some good answers about bent cannulas. The only thing that I'd add is that there are some infusion sets that don't have bent cannula problems, those that use metal needles. These include Minimed's Polyfin, Unomedical's Basic and Contact, and Disetronic's Rapid. While they're not for everyone (those sensitive to metals), they're not as bad as they sound. Actually, I've found them to work very well.

 

David

 

I would sure as heck hope you NEVER get a bent canula with a needle set. That would hurt like ********************.

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Mariel's Mom
Bent canulas can happen for a number of reasons and it's almost impossible to predict. A bent canula usually comes from inserting the canula and hitting something harder than fat, whether that is muscle or scar tissue it's unknown (since you can't see inside your body while inserting.) They can also come from pushing on it after it has been inserted. I'm not saying don't push on it, but you have to remember the needle is no longer there to assist in the inserting. Therefore you have a soft pliable plasting pushing on a hard fat (harder than the plastic) and that can cause it to bend. Some people choose not to lay on insertion sites. But in my 4 years of pumping I lay on them quite a bit. And have only seen a handful of bent canulas and many which actually still work and I don't see them bent till my 72 hours is up.

 

What does a bent canula look like? Take an old canula sometime that isn't bend and simply bend the end about 1/16" down in half. That's a bent canula. It would look like the end of the tube was crushed and not straight. It usually, 99%+ of the time will be at the very very tip of the canula.

 

How can you tell if it's a bent canula or not? It's really hard to tell a bent canula from a bad insertion site. There are many reasons each one may occur and the only obvious one is an unexpected rise in BGs that you can't seem to get down. You can have both immediately after putting a new insertion site in. That's why they recommend not changing infusion sets 3 hours prior to bed.

 

Great Info Master Jedi, but...since the bent cannula and bad insertion site can be two different things (a light is dawning in my head) - what is a bad insertion site and why would that impede insulin delivery if the cannula is not bent?

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JediSkipdogg
Great Info Master Jedi' date=' but...since the bent cannula and bad insertion site can be two different things (a light is dawning in my head) - what is a bad insertion site and why would that impede insulin delivery if the cannula is not bent?[/quote']

 

A bad insertion site can be many things. It can be one where you hit muscle. Muscle absorbs insulin extremely slow. Most of the time though, if you hit muscle, you will feel it for sure.

 

It can also be a spot that has built up scar tissue, although it takes many many years to develope scar tissue unless you don't change sites every 3 days. This is why site rotation is important and I try to stay away by 1 inch from sites that have been used in the past 2 weeks (usually a red dot shows still on me.)

 

Another is high amounts of fat actually absorb insulin slower. Blood doesn't flow alot through fat. Therefore if there is alot of fat, it can take longer for it to absorb through the fat and into the blood stream. That is one reason why one should stay away from the belly button area. Since high amounts of fat take longer for insulin to be absorbed through, it can take so long that it can make the insulin die out. By that I mean once you inject, insulin has a very short life cycle. That's why creating a once a week type Lantus is extremely hard because the heat in the body kills the insulin off.

 

Another thing to do with high fats is that in some areas there may be less blood vessels than other areas. Therefore if you get an area that has few vessels the insulin has to "spread out" further to find a vessel so it gets into the blood stream to be carried throughout the body to the cells.

 

And finally, the expiration on the insulin. Insulin does have an experiation time and the closer you get to it the less potent it becomes. Lantus is a prime example of this as many find when they get to the 30 day mark on a bottle, it's about dead and it just dies off extremely fast.

 

The idea method would be some x-ray vision machine that we could see are veins and muscles and place the canula right next to a good healthy vein (but far enough away to not break it), but not near muscle. But that's not going to happen anytime soon.

 

And you don't need to call me a Master Jedi, although I have studied and become adept to the ways of the Force.

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HollyB

Just wanted to send my sympathies for such crummy luck -- the last thing you want is a bad set the very first time you do a change, especially with a kid. It's not such a small thing for a kid to have to turn around and change it all over again!

 

Aaron uses two sets -- the Comfort short (angled) and the Quickset, and so far the Quickset has been more finicky -- we had one we pretty much knew was going to be bad because the tape stuck to the side of the inserter on the way in, and another that seemed all right but it was a bit finicky getting the inserter off and we think we might have joggled it around too much. The short straight-in sets seem to need to go in straight and fast, and then not be moved around at all before they're securely taped down. When we pulled them out, the one was obviously bent but the other just a little off-kilter, like you describe only more so.

 

Good luck with your next tries~!

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spike
I've been wondering the same myself. I also use the Insets and have not had a single bent cannula. At first, I was cautious to not sleep on a site, etc., but know if it doesn't hurt, I just get comfortable. So how do these cannulas get bent? I just got a box of 6mm to try, rather than the 9mm. Are these going to be more prone to bending?

 

None of my 5 bent cannulas have resulted in any discomfort--just a lack of insulin delivery!

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jenet
What does a bent canula look like? Take an old canula sometime that isn't bend and simply bend the end about 1/16" down in half. That's a bent canula. It would look like the end of the tube was crushed and not straight. It usually, 99%+ of the time will be at the very very tip of the canula.

Thank you! I have been wondering for months if I would be able to recognize a bent cannula if it ever happened. Now I know it's almost always a clearly visible bend or definite kink - not just the whole cannula tilted slightly off the 90 degree angle. One less thing to worry about!

 

cheers,

j

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Belinda

My very FIRST one that was inserted at the doc's office was bent...talking about frustration.....it happens and sometimes you can remove an old site and look at it and it is bent and you wonder....how did this ever deliver insulin but it did. There are various factors as mentioned but my rule of thumb is I check two hours after I change site, if it is higher than it should be I send in a correction and check again with in an hour...if my BS is not coming down then it is the site. I change it (which is not that often ...maybe 1 in 25 changes if that often). I also take an injection to compensate for the high instead of trying to pump in that insulin with a new site. Remember, this works for me...may not work for others or you may find a better way to deal with it...

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Tim_Roy

I don't really ever have this situation (I use Silhouettes). From time to time if it nicks a blood vessel on the way in, my insulin absorbs too fast, giving me lows which are followed by highs. Not fun either, but they don't happen every day and you can usually tell by how it feels going in.

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