position of cannula?

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Hi all, been thinking about the steel jobbies today and trying to find out why they need changing every 2 days compared with 3 days for teflon?

Tried googling, reading Pumping Insulin....recommendations and generalised reasons why sets fail but not a reason why the 48 hours need to change for steel. Any ideas anyone?

There's this tunnelling effect which occurs if sets are left in too long but with short straight cannulas can't see that would happen much sooner with steel. Maybe body reacting to metal more quickly than teflon, but it's the insulin itself I thought which causes antibody build up or crystallisation??

I hate not knowing reasons why! And therefore what the risks are with pushing things to the limits (please don't tell me off anyone ;-) )
 
The reason the steel cannulas are changed every 2 days is due to scar tissue build up same reason as the tethlon is every 3 days. Different materials cause scaring at different times.
 
Thanks Sue. Do you think that it's because of the rigidity of the metal compared with softer give of teflon causing tissue damage more quickly? Even though they're very fine compared with teflon. As far as I can find out, steel is well tolerated (unless people have a nickel allergy as there's also some nickel in the cannulas), so it must be more than just the material itself?? I think I need to phone the pump co.s, problem is it's in their (financial) interest to recommend more frequent changes ;-) It's just odd that it's not that easy to find the reason behind the official recommendation!
 
Hi Ingrid, I doubt there's any financial gain for the company's as the steel cannulas are cheaper. Besides there no way the NHS would pay more for that option.
I did try the steel cannula and have to say after 2 days it was more than enough having it stuck in me. Personally I wouldn't want to risk going over the stated time of use as can not see the damage being done for the future.
 
Ha, at last I've found an up-to-date paper http://dst.sagepub.com/content/early/2014/02/26/1932296814523882.full

including this gem of a paragraph (IIS = Insulin Infusion Sets) :

Length of use recommendations for IIS is generally 2 days for steel sets and 3 days for Teflon sets, although we are unable to find any data supporting these recommendations and at least one study found no difference.
Click to expand...

I'm afraid the NHS is ripped off left, right and centre by pharmaceutical co.s, powerful lobbyists, undeclared interests, clever marketing, distorted and hidden trial results.....I'm not saying it is in this case, but I don't take anything at face value when I know the potential forces at play 😉 🙂

All I was really asking was whether anyone here knows what these 2 different recommendations for set change (teflon vs steel) are based on exactly, and what evidence there is for it (the difference)? As it stands, the different pump co.s recommend different lengths of time for both tubing and cartridge changes (at least Animas and Roche do, don't know about the others), presumably based on the same research evidence!

I know in the end we also have to find out what works best for us, within the information we are given, or can access. But I would hope the starting point is based on sound well-researched evidence, and there just doesn't seem to be any regarding more frequent change of steel cannulas!!

Gah....brain in overdrive. Thanks anyway for your input and thoughts 🙂
 
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Thanks Ingrid, very interesting article. Personally I have no change in absorption between day 2 or 3 of cannula being in, and I for one do not want a foreign body stuck in me for more than 3 days. 2 days was more than enough for the steel sets anyway. I would also be interested to know the outcome a few years down the line if people don't change their sets regularly i.e lumps and bumps under the skin.
 
I do 3-4 on my right side, then 3-4 on my belly and then 3-4 on my left side

And repeat!
 
I tried a new place for the cannula two days ago - I have limited places to use because of scarring and lumps and hollows caused by too many years on MDI. But it wasn't good. I've had results in double figures for two days despite changing the cannula after day one. I did a complete infusion set change this afternoon, went back to an area that has worked well before, and glad to say now back to normal results. 🙄
 
Just to throw a spanner in the works and add another variable! I was told that once my vial was in use it was to be kept out of the fridge. One thing I discovered a while ago is that insulin is light sensitive, so it can degrade if it's not kept in the dark once out of the fridge. The second thing I have noticed is that whilst my vials are no way kept out of the fridge for more than 30 days, by the time I get to the 4th fill (I would normally keep a set in for 6 days with a cannula change every 3) that the insulin is decidedly less potent and I will be seeing double figures. If I then change to a new vial it's like having a different and more potent insulin and I'll be back to single figs again. I am experimenting with putting the vial back in the fridge in between set changes and only removing it a short time before a reservoir fill. I'll let peeps know how it goes.

This may only apply to my insulin which is Apidra.
 
Hi Patti, I have never left my insulin out of the fridge. It comes out 30 mins before a refill is needed and goes straight back in again.
On my previous pump which had a bigger cartridge my insulin lasted at least 15 days with no problems. 🙂

I have no absorption what so ever top end of bum or thighs so just use a very careful rotation for tummy.
 
I still think my results are affected by temperature. I keep the current bottle out of the fridge, in its box in a drawer, so don't think it's a light issue. The first two days after a refill I get good results but after that they start creeping up and up. I have to refill every four days but change the cannula every two. I can only think the problem is caused by the insulin keeping warm next to me.:confused:
 
If it was the insulin warming up, you would have to refill every two days, not four. So it is the cannula itself, or rather your skin/subcutaneous fat surrounding the cannula - it becomes irritated gradually to the presence of the cannula, and starts to absorb the insulin less well - my son has the same problem and also has to change every two days.
 
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