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Artificial-Pancreas / iAPS

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Medtronic pumps (maybe pods too?) continue to “dose insulin” after reservoir if empty. #241

Open tqb43 opened 1 year ago

tqb43 commented 1 year ago

A user on Facebook noted that she fell asleep and her Medtronic reservoir hit 0. She slept for about 6 hours with the empty reservoir but during that time iAPS continually calculated and “delivered” basals and SMBs.

Obviously, she wasn’t getting that insulin but she woke up with a massive amount of false IOB.

I suggest once a reservoir hits 0 to put the pump into suspend mode.

not sure if pods behave similarly.

LiroyvH commented 1 year ago

I think you actually do get that insulin on Medtronic pumps though. I've seen similar behavior with my Medtronic 754 and 722's: both can say 0 units remaining, and iAPS shows the same, but it continues delivering insulin. You can hear and see the motor moving and when I detach myself from the cable: insulin comes dripping out. At some point, it truly comes to the end and then it throws a Motor Error/Fault. Typically I think once it hits 0U I have at least ~20-25U remaining. Once I get a Motor Error I think iAPS jumped to Red Loop as well as I got "iAPS has not been active for xx minutes blabla".

So with that in mind, is she absolutely 100% positive it was "false IOB" and not actually delivered insulin...? The Medtronic saying 0U remaining is more of a safe-side estimation than that it seems to be true. I'm quite liking this margin tbh.

csidrak commented 1 year ago

Hi! I’m the Facebook user he’s referring to. As I was saying in the fb group, I woke up with a BG of 426 so I’m entirely sure my reservoir was empty for several hours.

Chester-sk8 commented 1 year ago

When I used 722 pump without iaps it were about 20 units in reservoir after 0 in pump’s info

LiroyvH commented 1 year ago

Hi,

I tried again, but cannot reproduce this problem. Here are all the details:

Setup:

Expected: pump stops delivery once truly empty and throws error, iAPS must error out subsequently.

Actual result: The Medtronic says 0U remaining, but continues delivering basal, SMB and boluses/bolii/whatever. Once it's really empty: it throws a motor error, including audible alert, and suspends insulin delivery.

The result of the above is:

NOTE: This process was done, albeit by accident, on prior occasion with a Medtronic 722 with an EmaLink and OrangeLink connected, with the exact same configuration and the same result.

Conclusion: Cannot reproduce, pump and iAPS behave exactly as expected with proper errors, sounds, notifications, IOB and bolus history. Maybe the setup is different, in which case more information is required about the user's setup and it might be useful to try and repeat inducing the failure state; but this time in a controlled setting, in a safe and responsible way if user is willing to do that and understands the potential risks. (Eg: under or over delivery, DKA, etc.)

Remember: safety first! Do not attempt doing it unless you know what you're doing and fully understand and accept the (potentially lethal) risks. Doing it whilst disconnected from the pump and with a backup delivery method available is safest; but remember iAPS may then have wrong IOB and TDD data for a bit and may act on it. Consulting a healthcare professional may be advisable.

csidrak commented 1 year ago

@LiroyvH Thank you for testing this issue out. I'm not sure which of my iaps settings, if any, may have contributed to the experience I had with iaps continuing to deliver SMB while my reservoir was empty, but suffice it say that I'm keeping a close watch on my pump reservoir volume before I go to bed now!

LiroyvH commented 1 year ago

@csidrak Yeah I can imagine so. The problem is pretty much that the pump reports back to iAPS that it's still delivering insulin; and in my experience and testcase, and by the looks of it also in @Chester-sk8's case, it actually does deliver it until it errors out. I seem to recall that a few years ago, Katie DiSimone (RIP) also wrote about this phenomenon and how the Medtronic's always estimate the 0U remaining wrong - but the documentation of Loop has been overhauled so many times and relocated multiple times, I can't find it anymore.

Also, out of curiosity, what was your pump event history showing?

If you're able to test it sometime, for example by - when it says 0U - disconnecting from your body and then trying to bolus like 5U a couple of times and see what it does (insulin dripping out?) (you can delete it from treatments later) and whether or not it errors out; that'd be helpful. Stay safe though!

Chester-sk8 commented 1 year ago

In addition can say that when you fill reservoir with 300U, medtronic’s pump and iaps show only 280u. This is exactly those “lost” 20 units which you can use when iaps shows 0 Sorry for my non-brilliant English)

csidrak commented 1 year ago

@LiroyvH, I switched to Dash pods 3 days ago so I don’t think I have access to the pump event history for Oct 9 (which was the day I had the issue with iAPS delivering non-existing insulin to my medtronic pump via SMB).

I may go back to medtronic at some point (I still have probably 5-6 months of supplies), but needed a break from some of the other issues I had with it, mainly the frequent yellow and red loops which seems to be expected if I were to continue looping with medtronic and iAPS.

I do really appreciate your guidance in trying to troubleshoot my issue. Hopefully I’ll never let my reservoir go empty again since it was pretty frightening to have had such a high blood sugar when that empty reservoir event occurred.

csidrak commented 1 year ago

@Chester-sk8 your English is great! I would have never thought there could be a 20 unit discrepancy in medtronic pumps. I wonder if it is specific to certain medtronic pump models? I’ve only ever used 522 and 722 medtronic pump models.

Chester-sk8 commented 1 year ago

@Chester-sk8 your English is great! I would have never thought there could be a 20 unit discrepancy in medtronic pumps. I wonder if it is specific to certain medtronic pump models? I’ve only ever used 522 and 722 medtronic pump models.

I’ve only used 722 pump and as I see this is usual situation when I fill a new reservoir with 300 units (I have insulin in flexpen with 300 units) and pump shows in statistic only about 280-283 units. For filling reservoir I use about 7-9 units. Yesterday I refilled my already used reservoir which contained some numver of units by new insulin (bad way but I wanted to test) and iaps shown 302 units after start but in a minute has changed it to 282:) I’ve asked guys in tg chat and they have answered that there is the same situation with 715.

LiroyvH commented 1 year ago

@csidrak Alright :) Just let us know if you do go back to Medtronic again and end up testing it. And you're welcome!

Also, not sure why when using Medtronic you should be expecting frequent yellow/red loops. I'm using iAPS with a Medtronic as well and it's quite rare to get yellow and even rarer to get red (other than when suspending for shower and such, but that doesn't count. :)) Maybe if you do go back to Medtronic we can look at troubleshooting that as well.

Enjoy the Dash! :)

csidrak commented 1 year ago

I’ve been on medtronic for so long for my pumping years that it actually feels weird not to have tubing and I didn’t mind carrying around the orange link. But I just was constantly troubleshooting the yellow and red loops almost daily. I had similar issues when I used medtronic and orange link for DIY Loop app back in May of this year, so I figured the communications between the orange link to the pump was just not great.

This is everything I tried:

I tried all of the above with both my 522 and 722 pumps and still had issues.

Is there anything else you recommend I try?

(I can switch back and forth between Dash and medtronic as long as I remember to change my basal rates.)

On Wed, Oct 18, 2023 at 7:51 PM Liroy van Hoewijk @.***> wrote:

@csidrak https://github.com/csidrak Alright :) Just let us know if you do go back to Medtronic again and end up testing it. And you're welcome!

Also, not sure why when using Medtronic you should be expecting frequent yellow/red loops. I'm using iAPS with a Medtronic as well and it's quite rare to get yellow and even rarer to get red (other than when suspending for shower and such, but that doesn't count. :)) Maybe if you do go back to Medtronic we can look at troubleshooting that as well.

Enjoy the Dash! :)

— Reply to this email directly, view it on GitHub https://github.com/Artificial-Pancreas/iAPS/issues/241#issuecomment-1769603839, or unsubscribe https://github.com/notifications/unsubscribe-auth/AEWVLGJBHNQLFUM7NKJM6TDYABTOTAVCNFSM6AAAAAA5Y7A73OVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMYTONRZGYYDGOBTHE . You are receiving this because you were mentioned.Message ID: @.***>

Chester-sk8 commented 1 year ago

But which iphone did you use with iaps? Maybe we are making troubleshooting in the wrong place?:)

csidrak commented 1 year ago

@Chester-sk8 I am using iPhone 12 Pro, iOS 16.6.