Hi Austin's Mom.
I routinely fill my cartridges completely. I use a similar amount of insulin (20-25u/day) and a 200 unit reservoir lasts me about a week. I even refill it once, so get 2 weeks out of a cartridge. (I use a sterile 3ml syringe from the feed store to refill so as to avoid contaminating my insulin vial). I haven't had a problem with the insulin (Humalog) lasting a week close to my body (98.6 degrees, right?), winter or summer.I just replace the set as needed, reuse the tubing.
The backpacking trip sounds wonderful!
Ha! I always tell my husband he has the sense of humor of a 13 year old (farts, burps, gross puns etc.) Good thing I love him so much cause I don't think he's gonna grow out of it...
For my daughter I fill a cartridges full and use it (and the same tubing) until empty. Her infusion set changes happen separately and this system works great for us. We don't reuse cartridges. I think we waste less insulin this way as we aren't changing tubing and priming so often. If it's really hot on your son's trip maybe he'll see rising numbers eventually and that would be his cue to put in a new cartridge with 'new' insulin that he's carrying in a cool pack.
I recently did a big backpacking trip in the very hot southwest (late August/early September). I did prefill a couple of cartridges and I did also change the infusion set and leave the reservoir in because there was enough insulin to last me for another infusion set cycle.
BUT, I did notice that the insulin became less effective by about the 5th day. It still worked, just not as well. My BGs began to creep up a bit, but thankfully this worked out well because the activity I was doing was so intense that I didn't experience any significant lows. Now, we were in temps that were regularly in the upper 80s. Down in the canyon it didn't get below 70 at night, although at the rim it dropped down into the 50s.
His TDD is about what mine is. When I was hiking/camping, there were some days where I didn't need more than 15 units, which was AWESOME.
I did prefill 2 reservoirs and stored them in a Frio pouch, along with my extra insulin.
A few (unsolicited) backpacking/D tips:
Sorry if this is more than you needed. I go backpacking a lot and have learned a few tricks backpacking with D. It definitely adds an element of difficult to any backpacking trip, but that just makes the experience more fun (when you do it successfully, at least!)
I go camping often, and I try to re-fill before our trips but I still need to re-fill every so often. The worst thing you can do is fill his cartridge enough for 3 days and expect nothing to happen, lol. I guess because this has happened to me before I am suggesting you have a back-up, and back-up for your back-up. So if I go camping for 3 days, I bring 2 infusion sets and reservoirs, you never know what will happen.
Being outdoors in those temps too, I would be worried about insulin degrading. What I use for my pump is a frio pack, a little more bulky than I like but it keeps the pump cooler than 90 degrees. You can also buy frio packs for your insulin vials. Let me know if you have any questions.
If you are concerned about his site coming out, when I used to play soccer and go to overnight camps, there was this liquid "glue" that kept the infusion sites intact for 3+ days. That stuff is amazing. It isn't IV Prep, you can see what you can get from your pump company.
By chance is he going to Philmont? I have no useful advice, but my brother has gone there for the past few years first as a boy scout, then eagle scout, then leader. It's an awesome hike I hear! I hope he has fun!!
I know this is old - but I thought this may help - I go a fair bit of tramping (the NZ term for hiking), my profile photo is from near the top of the Routeburn Saddle.
I carry a little bottle of dishwash liquid (as you need to clean your cooking equipment and plates each night (all the stuff we do is self sufficent, and use this for hand washing, and I also carry a ziplock bag with a few wet wipes, either standard or disinfectant for water free hand cleans, if I need to change out a site where there is no water. As I do some alpine/subalpine tramping, there isn't always water/creeks near by. I also routinely reuse cartridges - once you draw out the insulin, you never push it back int he bottle - if you need to get ride of bubbles, remove the cartridge and air shot, don't push it back into the bottle.
This may be a stale thread, but I too have a couple of things you might find helpful:
HibaStat makes a towelette-style wipe that comes in individual packages. Very handy for site prep in the rough country.
We don't carry the bottles of insulin to refill the reservoir. Instead, we carry an insulin PEN with a couple of extra cartridges. The cartridges are 300 units, which lets you fill a reservoir completely with plenty left over. And of course you still have the pen as an option for backup if the pump goes out.