First day with t:slim x2 pump +Dexcom G6. No problems until dinner when, halfway through bolus, I got an occlusion alarm. (This after a whole day of basal/bolus delivery without problem and perfect BG). I hit resume delivery, but apparently it didn’t provide the remainder of the bolus so i just calculated what was missing and added it in. No problem this time. Given my continued no-problem BG, and what I’d read online about this being a Tandem issue, I decided to just stay up a few hours later and watch instead of calling customer service. I should mention I was previously a Medtronic pumper. On that pump, if there was a delivery problem (which was rare) it was a permanent problem requiring a change of infusion set. Not the same with the t:slim? Any wise words will be appreciated!
hi @elizabethm, actually, it depends on why there was no delivery. My infusion set (and medtronic pump) is high on my hip and very near muscle. I JUST GOT a no delivery for dinner and so I stood up and resumed and then delivered the remainder… it was fine. It even stung a little. anyway I successfully got the bolus bc the infusion set must have been squeezed by the tissue it is in, in that position.
anyway, glad it worked out this time but noting worse than a wonky site that fails outa nowhere.
most pumps use a pressure sensor and if the motor cant push insulin the pressure goes up and triggers a occlusion alarm typically “No delivery” To tell another story, my tubing once got pinched under my belt and that cause a no delivery, which I also recovered from when I unstuck the tubing… a long time ago. most times I do have to change the set.
cheers good luck.
I’ve been using TSlim for over 10 years now and have rarely gotten those errors. Most often they go away on their own - in which case my theory is that it was caused by a kink in the tubing which rectified when I moved to check the alert. That’s If it continues I assume it’s scar tissue and move my site and that takes care of it.
Thanks, Joe. BG fine through the night, so assuming it was just a positional problem with the tubing getting squeezed, as you suggest.
Thanks, Dorie. Glad to hear these problems aren’t to be expected all the time with Tandem. It sure is controlling my BG. Just odd with T:slim to have to recalculate what I missed on my interrupted bolus. It didn’t seem to do that calculation for me. But I did the math and all well through the night, which is pretty amazing.
Hi Elizabeth @elizabethm, and welcome to the Tandem t-Slim x2 pump. In my humble opinion, you reacted properly to this event - OK, you did exactly as I would do.
I’ve been using my t-Slim x2 for 21 months and during that time, I’ve had a couple of flow-interruption notices; turns out, one of the notices was for an actual infusion-set fault. Prior to Tandem, I used three different MiniMed [Medtronic] insulin pump models; my major complaint with those pumps is that they were actually programmed to wait [?] hours after detecting an occlusion before notifying the user. The last MiniMed pump I used was purchased in 2014 so my previous statement may be “dated”.
One of the many things I like about the t-Slim pump is that it is [almost] proactive, and keeps me well informed - sometimes too well informed. Because of the “I’ll SUE” mindset of so many people [which has quadrupled healthcare costs], Tandem has built into its pump many, many safety features, including the flow-interruption notification, so that the user can make immediate treatment decisions. I have found the built-in “history” logs to be most helpful, and informative for my pro-active management style.
If and when you decide to use Control IQ [CIQ], I hope it works as well for you as it has for me these last 9 months. But before beginning CIQ, please validate app Profile settings, especially basal rates throughout the day. Having correct insulin sensitivity factors [ISF], is essential for accurate automatic bolus calculations. Good Luck!
Thanks, Dennis. I will likely wait to start CIQ until after I have followed up with my diabetes nurse to review all the settings. Just the BIQ is a lot right now! The insulin interruption notices have continued. Breakfast bolus was fine but same thing at lunch. Seems fine if I take it out of my pocket for the bolus. I’ve seen some suggestions on other forums that this may be due to a change in temperature and that the t:slim doesn’t work as well in a pocket, which would be unfortunate. Also, some have suggested that filling the cartridge with only the small amount of insulin I need for 3 days could be problematic. I would prefer to fill it for a week (tho of course that is frowned upon by the nurses and tandem reps). I found filling the cartridge much more difficult than with the medtronic pump. Appreciate your advice! I’m sure I’ll be asking for more… Thanks!
I used to do a week (or so) full but we’d told by my doctor that I should change sites more frequently so now I’m on a 3 day cycle, using somewhere between 30 and 35 units a day - no problems for me there. I usually tuck my pump in my pocket - that does not result in any inclusions for me but for some reason of I’m wearing denim and have my pump in the pocket opposite of where I’m wearing my transmitter, it can lose contact easily; moving it tries the connection. Be sure to wear the pump facing out - it’s tempting to want to protect the face by keeping it towards your body but that can interfere with the CGM/pump communication.
That leads me to ask where you live - do you have extreme temps or humidity? To be honest I’m grasping at straws but you never know. I’m in the DC area where we have heart and humidity in the summer, and cold tennis in the winter, but that doesn’t seem to bother me.
Another thing may be the type of infusion set you use. I used AutoSoft 90 d for a long time but didn’t feel confident that it wasn’t getting dislodged as I peeled off the backing; so I’ve been using the AutoSoft 30 instead, which goes in at an angle and I find easier to grab. There are also steel needle sets, which I hear are not as painful as they sound. I wish you could try a sample without committing to an entire box, but you should be able to order different ones. I believe doctor’s rx simply indicates which pump you need them for, and you can select your own “model,” insertion angle, etc from there.
Elizabeth @elizabethm, I too use the cartridge minimum amount, and sometimes let my infusion set stay in place for a fourth day just so i don’t waste any insulin; no problems. It is okay to put up to a week’s worth of insulin in a cartridge, and just change the infusion set every three days - I did this while traveling, not knowing if I’d be in a convenient place to fill a cartridge. Everything worked well.
Lilly has the caution / directive to discard any insulin that has been in a cartridge / reservoir for more than seven days; this warning is on Humalog and Lispro - I haven’t yet read the package insert for Lyumjev. Thinking back to a study of about 15 years ago, I recall something about insulin crystalizing after being stored in plastic.
I think it is wise that you wait before changing to CIQ. Use this time to monitor the effectiveness of your basal rates by observing when, and by how much BIQ suspends basal. The t-Connect application, and the Tidepool application give you a good picture of what your pump has been doing.
Thanks, Dorie. I am in Maine so extreme heat/humidity certainly not an issue for me. I have found over the past few days thought that if I leave the pump out of my pocket during the bolus, occlusion alarm does not go off as often. The autosoft sets I’ve been using are just like the Mios I used to use, and also don’t seem to be the problem. It is just taking some getting used to I guess…
Thanks, Dennis. So today I ripped the infusion set off and had to fill a new cartridge on my own for the first time. Didn’t go well, haha. This seems so much more difficult than the Medtronic, so I’m glad everyone seems to get used to and like the t:slim. I am def going to fill that cartridge up next time, or at least a week’s worth. One question I have is whether when it hits 0 units on this pump you can still go through the night, understanding there are prob 5-15 units still in there (as you can with Medtronic) or whether the pump will just stop and force you to change the cartridge. This would be so wasteful if, say, it approaches 0 at bedtime or when working somewhere. Lots about this to get used to and the manual is larger than my truck’s owner manual…and yet oddly seems to not include all I need…
Ah the Mios - I guess that’s what I was using with my Minimed way back when. Someone suggested to me a long time back that it might be helpful to switch up your insertion angle now and then to help with avast tissue or something like that. I don’t know if that’s true or not but thought I’d toss it out there…
PS - the system will alert you when you’re down to 5 units in the cartridge - and repeat until you take care of it. When you get a Low Insulin alert delivery could stop at any time.
Elizabeth @elizabethm, when the Tandem calculates that the cartridge is empty. it STOPS all insulin delivery. It doesn’t let you keep operating like the Minimed pumps. And, the Tandem will not let you forget that the cartridge is empty, and insulin delivery is stopped - it will send an audible alert every five minutes. Below is what I do so as to not waste insulin, and replace the cartridge in a non-stressed or excited moment. (I tried a couple of times to see if insulin is actually left on an “empty” cartridge like in the MiniMed reservoirs, and found by extraction attempts that there is not much more than a single unit.)
There are two (2) low reservoir alerts, the system set alert at 4 units which user can not change, and an optional user-set alarm at whatever volume we choose - I have mine set at 15 units. I find that filling the cartridge is not difficult or time consuming when I’m relaxed, so I often will fill a cartridge the evening before I know it will be needed; and a cartridge fits nicely into the box with the insulin vial. This will help me prevent having to discard unused insulin in a cartridge as well as not letting insulin remain in a cartridge for more than seven days. For example, if I will need 5 units of insulin to cover my breakfast, and the pump thinks that only 3 units are left in the cartridge, the pump message will tell me that my attempted bolus is to large and by how much; I reduce the bolus to the maximum allowed, let it infuse, and then relpcae the cartridge with the one I filled the prior evening, and then manually enter a balance bolus. Zero units of insulin wasted, and the cartridge is simple, un-pressured, and quick.
I use this same way of using all insulin in a cartridge. On days that I’m out-and-about [I volunteer different days], I will pack a filled cartridge, and when my pump gets to empty, the switch-out is very simple.
Thanks, Dennis. Those sound like great tips!
Also, I just went on to t:connect on my laptop for first time and the activity summary includes both a cgm summary (looking good!) and a “blood glucose summary” (looking awful!). Why/how are these 2 different things–I am not using a BG meter, only the CGM. Very confusing…
to be more clear in my question: one summary gives a perfectly fine “average cgm” and the other an awful “average BG”
Elizabeth @elizabethm, keep in mind what the two averages represent. The CGM average is of all body glucose readings, up to 288 per day - 2100 per week, while the BG average is of the very few fingerstick blood checks you enter into your pump. If you are like me, the only time I do a fingerstick, only a handful of times during three months, I ignore the BG graph on t-Connect. The total number of readings entering into the statistics is at the right of the page.
That’s what’s so weird. I haven’t done a finger stick at all since starting the tandem/dexcom! Yet it suggests I have done so dozens of times, with poor results. The 1,000 cgm readings appear closer to what I was expecting, so I will just go with that and, as you say, ignore the BG graph on tconnect.
Appreciate your taking so many questions…
I get occlusion alarms frequently. I’ve learned to note and calculate the amount not delivered. I wear my pump in a baby sock in my bra, with no slack in the tubing because any other placement results in catching the tubing with my finger, or on something. But if I curl up the tubing and put the pump away before the bolus is finished, I often get an occlusion alarm. So I put it in my pants or vest pocket temporarily.
Hi Phoebe @Ploxley you have found a clever method, but your method MAY be causing the “not delivered” issue. When you curl up the tubing, and pull it tight, you may be causing a “crimp” which blocks the insulin. Just a guess, so I suggest that you leave a little slack in the tube.
I had my first “occlusion” alarm today after almost a year of using my Tandem pump with true steel infusion sets. I have experienced bad infusion sites and bad insulin but not occlusions.
Yesterday I changed the infusion set. I had trouble the previous evening getting my BG back down in range and suspected that I had a bad site. Overnight Control IQ was able to bring my BG down as much as it could in sleep mode. In the midst of my extended bolus for breakfast, I got an occlusion alarm and saw that I wasn’t getting any reaction to the insulin supposedly delivered.
So I troubleshot it as a bad site. I disconnected at the cannula and give a test bolus of one unit to confirm that the insulin was flowing the tubing before replacing the cannula. Nothing came out.
That was a first for me. So I tried another 1 unit bolus. Again nothing came out and the pump motor didn’t sound normal.
After thinking about it I realized that I’d done one thing different when I changed the infusion set. I installed a new silicone “gel” case. So I slid the case off the pump, tested the pump again, and it worked.
I looked at the silicone case carefully. Where the pump has a vent in the back, the case had a matching hole - with a continuous film of silicone closing it off.
I opened the hole, reinstalled the case and have been watching the pump for the past 3 hours. I cautiously gave a partial bolus for the insulin that I don’t believe was delivered, and watched Control IQ react and flatten a post-breakfast rise.
The pump is now working correctly. I just need to compensate for what the pump incorrectly believes is my IOB for the next few hours and make a 2-3 unit correction before lunch.
This is what I think happened.
I don’t believe that the pump has an actual pressure sensor, but instead senses the motor current, which rises if it has to work harder to move the little stepper motor. One way to do this is to integrate or average the current during pumping over the duration of pumping and look for a trigger voltage across a lossy capacitor circuit and look at it after a charging cycle ends. Because the pump doesn’t run continuously during a bolus, but pauses at regular short intervals, the timing is known and the trigger value can be fixed.
With the vent holes nearly sealed, the low flow of the basal delivery wasn’t enough to draw the film tightly across the vent holes. The much faster bolus flow was enough to draw the film against the pump holes, and the pump produced enough partial vacuum for the film to stick in place.
In the manuals, there are two references only reference that seem to confirm this:
and the altitude alarm which talks about removing the cartridge and reinserting it after the pump is gone through an altitude change which would be a change in air pressure. Removing the case, relieved the partial vacuum, equalized the pressure.