Posted by on Saturday, 26 January 2013

Bubble, bubble, tubing trouble

Looking at my stats it seems Artoo has been having a bit of a run of form recently. Not without a wobble here and there obviously (let's not be silly) but certainly a decent punt at things on the whole, and far fewer eye watering levels in the 20s than in any of the months since I started on an insulin pump (which were never really part of my MDI experience). According to the funky monthly reports on my current BG logging app of choice (the excellent mySugr - 'making diabetes suck slightly less') my purple patch seems to date back to October. I even seemed to manage Christmas with fewer Quality Street induced gaffes than I would normally expect. Generally average BG in the high 6's low 7's (108-126), with an SD around the mid 2's (36). This makes me happy.

Aside from me taking a *very* long time to get used to the whole pumping business (Artoo was very patient with me) I believe there are a couple of changes which have helped me, so I'm posting this insufferably smug blog entry just in case there are any frustrated insulin pumpers who stumble upon it that are putting in all the effort but not seeing the results they are hoping for.

Firstly, September was the time that I switched infusion sets. I'd been having a fair few failures for some months, but only in amongst a majority of set changes that worked perfectly. At the time it was less obvious, but looking back, a readings/recoveries from mid 20s almost every month were messing things up for me. If you are getting set failures/site issues more than a couple of times a year it could well be worth asking your clinic/DSN/endo what alternative lengths and types of infusion sets are available to you. I've not had *one* site failure in the past four months - and aside from the lack of eye-frying levels, it also makes me feel a lot better about the whole business of diabetes day to day (as hard as I try not to part of me always takes these out of range disasters as a sort of personal failure).

Secondly, and my initial reason for writing this post, I think I have cracked the 'bubbles in the tubing' problem. Maybe not 100%, but pretty darned close. I'm not sure how common this is, but throughout my first year on a pump I was occasionally victim of a 'phantom bubble of doom'™. I'd fill the reservoir with room-temperature insulin as advised, having first moved the plunger up and down to lubricate the inside of the reservoir. I'd flick and jiggle for all I was worth until I was absolutely sure that there were no bubbles in the insulin. Fit the reservoir to the pump, and prime with the pump vertical, tapping all the while to ensure that any rogue bubble-ettes got expelled in the priming, and then connect everything up happy in the knowledge that I had achieved the perfect bubble-free set change. BUT. The next day, look at the reservoir and BAM, there it was a big, fat, lurking, bubble of doom. Ready and waiting to find its way into the tubing at some inconvenient moment and then effectively deprive me of basal for an hour or two. Or mess up a meal bolus. Or both. I do try to check my tubing a few times a day but these suckers are hard to spot. And just as frustrating as the high BGs they caused - was not knowing where they were coming from! I was as sure as I can be that they were not there when I changed the set. They just seemed to be emerging out of nowhere with an evil glint in their eye overnight.

I did discover a suggestion on You Tube, which I won't link here as it was a complete disaster for me. The technique (described as something like 'degassing the reservoir') involved creating a fairly strong vacuum in the insulin vial by repeatedly drawing air out of it until you could do no more. Do not try this! My experience is that reservoirs are just not designed to operate under that kind of pressure. On more than one occasion (and I only tried it about 3 times!) the o-rings failed and insulin began to leak 'behind' the plunger while the reservoir was in use. Complete BG chaos. But it did get me thinking...

If you too suffer from occasional 'phantom bubbles of doom' - here's what seems to be working for me. When you draw up the insulin into the reservoir it is usual to first inject air into the vial, equivalent to the insulin you are about to withdraw, to equalise the pressure. Instead of this only inject half of the air into the vial. Additionally you should make sure that you inject the air with the vial downward, then invert the whole caboodle to draw up the full insulin amount. Then flick and jiggle any bubbles that have crept in as normal. Disconnect the reservoir first, to allow the air pressure in the vial to normalise again. It seems that the very slight vacuum created is not enough to worry the o-rings, but is sufficient to make the insulin less 'aerated' in the reservoir. Or something. Anyhow, it seems to be working!

Obviously... Disclaimer, disclaimer. Not medical advice. Consult a qualified person. Don't try this at home. Read the documentation supplied with your pump. Simply reading this blog post may void your warranty etc etc.

If you have any top tips that you have discovered for yourself - please share them below :)

3 comments:

  1. Hi Mike,
    same problems here! Bubbles have been happening on a regular basis in the last month, I wonder if this has something to do with cold temperatures and the insulin being at body temperature.

    I do pretty much the same as you do, except that before withdrawing insulin I keep the vial in my pocket for ten minutes to let the insulin warm up a little (DSN suggestion). I'm not sure if this is good advice really, I sometimes wonder whether moving around with a vial in my pocket might add even more bubbles into the equation...

    Manu

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  2. Interesting thought!

    I've only ever been told about getting the insulin up to room temperature for the first use out of that vial (to help prevent 'champagne' bubbles). I keep the vial out of the fridge from first use until it is empty as this takes less than 28 days for me.

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  3. I don't know which pump you're using (I could probably find out by reading a bit more...) but I've found filling the reservoir the night before the change (I usually change my sets in the morning before breakfast) and then letting the thing stand upright over night, helps a bit. I guess any of the irritating "almost impossible to see" bubbles then get a chance to settle to the top into one big bubble which is easier to prime out. Whereas if you load the reservoir straight away into the pump, the bubble amalgamate then and can pose a problem?

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