....if different pumps, even of identical model and brand, deliver slightly different amounts of insulin when set at the same rates?
I'm not thinking differences in the range of entire units, but maybe 0.01-0.02 unit differences in delivery when set at the same rates, due to minute differences in the mechanics.
The reason I even ask this question is that when I changed my infusion set first thing Monday morning this week, I also switched to the pump replacing my old, cracked one, and ever since I've had way more hypos than usual. Actually to the point where there are almost as many readings below 4.0 mmol/l as there are between 4.0 mmol/l (72 mg/dl) and 8.5 mmol/l (154 mg/dl) (my desired range). I've only had one high reading Tuesday morning after overtreating a pre-bed hypo in fear of more hypos after a day with no less than 10 readings of 2.1-3.3 mmol/l (38-60 mg/dl)!
I'd entered all my settings with my old pump in one hand and the new one in the other, reviewing them all multiple times to be sure that there were no discrepancies. The significant number of lows could of course be caused by something else and in this sense be totally coincidental, but I do find it strange that it's been like this since Monday. I'll await how the numbers behave after my next site change before I start tweaking basal rates and ins:carb-ratios. Until then I'm wondering about pumps, precision and performance - as well as how I avoid the next hypo :-)
A couple of months ago or so, I noticed that my pump had some cracks on each side of the reservoir window. I made a mental note to inquire about this the next time I saw my D-nurse, and then forgot about it again - well at least until the next time I saw a crazy number that called for inspection of tubing and reservoir for air bubbles :-)
The cracks are visible as thin white lines on the above pictures, my apologies for the poor quality of these, but close-up detail coverage isn't a force of our camera ;-) The cracks actually go all the way into the reservoir window, which on more than one occasion has made me question whether the reservoir was damaged, even if it was bright new and I hadn't noticed anything when filling it up.
Last week, I had an appointment with my D-nurse and showed her the cracks (in Denmark, insulin pumps as well as the supplies are paid for by the hospital treating you, hence I had to ask whether they would want to just replace it or if I should contact the pump company rep about it). Turned out, the decision and way of replacement would depend on whether the warranty period had expired or not - neither of us could recall exactly when I had gotten the now cracked pump.
A call to the company rep revealed that my current pump was still under warranty and so the company would send an identical replacement model (if the warranty period had expired, the hospital would have provided me with the newer Paradigm Veo). So now I have a replacement pump to set up before I retire the old one by direct mail to the company :-)
