Flying and variation in pump output

Tips, Tech & Gear Pump
1

The subject came up in a discussion with @TravelingOn recently. It turns out that there is some evidence of slight variations in insulin delivery from a pump when flying, due to variations in atmospheric pressure.

This study (King 2011) discusses an experiment with separate 10 instances of pumps:

Essentially, the study shows slight over-delivery of insulin (0.7 U) during ascent and slight under-delivery during descent. These numbers are heavily qualified by the conditions of the study, which, however, reports more than 50 instances of hypoglycemia in children while flying. The study also proposes recommendations for pump users. The most striking conclusion, however, is that explosive decompression would lead to large release of insulin (8U or more)

The study was criticized by Prof. Hirsch of the University of Washington School of Medicine, whose comments are cited in this article (original paper unavailable on line at http://online.liebertpub.com/doi/abs/10.1089/dia.2011.0190):

His argument is that the sample is small and the variations limited.

In turn, his critique was replied to by the original authors:

http://online.liebertpub.com/doi/full/10.1089/dia.2011.0223

My take-away: the variations may be significant to toddlers, but don’t seem of real importance to teenagers or adults. Explosive decompression, however, is worth reading about.

3 Likes
2

I think that explosive decompression on a modern airline is exceedingly rare, considering you would need to lose a section of aircraft skin to achieve this. i.e. a small hole or a mechanical failure in a pressurization pump wouldn’t result in explosive decompression.

There have been a couple of cases in recent memory, but honestly, when your plane starts disintegrating, insulin will not be at the top of your list of worries.

Having been in a military altitude simulation (pressure) chamber and experienced explosive decompression, it is a cool thing, except your ears aren’t designed for it. :wink:

2 Likes
3

The insulin released by the pump from the decompression would probably balance out the BG spike you would get from the adrenaline surge, as you realized you are about to die. :flushed:

6 Likes
4

Funny!

But not accurate. Explosive decompression typically does not lead to the loss of the plane. Many planes every year experience explosive decompression due to small body collisions or system malfunctions, then land with all or most of their people on board.

1 Like
5

I don’t have a reference, but I think you are overstating the rate of explosive decompression. There are cases every year of gradual to rapid decompression happening through mechanical failure of the pressurization systems, but this isn’t explosive in nature. In order to get explosive decompression you need to have a pretty big hole in the fuselage of the aircraft. This doesn’t happen that often, although it does happen. Either through metal fatigue (last case I remember, Hawaiian airlines), or explosives. When they train you for it, they put you at 8000 feet, then take an antechamber to 25,000 feet then open the door between the two.

2 Likes
6

Well, regardless of whether you actually die, I guarantee you will not have low BG after that happens to your plane. Spike city!

Do you know the feeling you get when cold chills or shivers instantly run up your spine from fear, and your heart suddenly starts racing? That type of feeling results in a BG spike.

3 Likes
7

I get that feeling multiple times a day, when I hear my wife’s voice going “Michel?” while raising the pitch on the second syllable :slight_smile:

2 Likes
8

You are right, I was actually thinking of rapid or sudden decompression, i.e. sudden and unexpected loss of pressurization when the pressure loss occurs in a small number of seconds (it’s the same thing as explosive decompression, but happens in seconds rather than instantaneously, and would result in the same insulin injection problem). There is a 20-some year old study on that, which reports about 50 such accidents per year, pretty much none of which result in the loss of the plane. I tried to find this study to give a link to it but somehow I can’t locate it right now.

1 Like
9

Anyway, I can say that we have flown 5-6 times with the pump and observed no issues in our teenagers bg. We thought about disconnecting during descent, but forgot. I will certainly inform my son to check his bg if the plane depressurizes. That said, I have flown a lot over the years and haven’t experienced a decompression event.

3 Likes
10

Thank you for the research! I believe I will look forward to reading it more closely in the near future. Alternatively, it might give me that feeling of cold chills racing up my spine, what with the airplane decompression component. I agree with @Eric that for the average passenger, the rapid loss of cabin pressure would be alarming and cause a stress related spike. In @EricH’s case, it would not surprise me if the plane depressurized and he did not feel concerned about it. He’s the type of guy that you will be sitting next to on the plane, turbulence lifting you off the seat, and he will be reading a science fiction book and not blinking an eye. He will be prying my fingers off of his reminding me to not break his hand in midair.

4 Likes
11

Folks in my endo’s office seem to think that time spent at 8,000 ft of altitude (near Denver) can contribute to big changes in insulin sensitivity or some other unknown mechanism that could account for poor blood sugar control.

If that is the case (and I am a bit skeptical, probably due to the lack of specificity), then flying in a jumbo jet should probably also impact a person similarly (assuming the flight is long enough for the mystery effect to occur). Planes are not pressurized to “sea level” atmospheric pressure.

Anyone have any guesses as to what effects occur at altitude? I’m not talking about Mt Everest or freezing cold…

1 Like
12

Some medical professionals have hypothesized that higher hormonal levels due to mid level altitude stress (possibly caused by slight hypoxia) could cause both elevated BG and increased insulin resistance.

I am still early in my altitude research though.

13

We travel frequently to Denver from close to sea level. We haven’t noticed any issues in control that can’t be linked to food intake when on vacation.

2 Likes
14

I wear an Omnipod and I have experienced two serious lows approximately 90 minutes after take-off due to air pressure changes. In both occurrences, I had eaten food just prior to boarding and injected after boarding and pre-flight. Never do this, especially if you are a child or a type 1 Lada that is seriously affected by 1 - 3 units of additional insulin.

I do believe, after quite a bit of experience flying with a pump (both animas and omnipod), that there are air pressure changes upon takeoff and landing that affect insulin delivery. Perhaps in some individuals that take quite a bit of insulin (compared to children or lada’s), the excess insulin given on takeoff cancels out the decrease in insulin on the descent.

For others, like me, like other lada’s and children, that are quite sensitive to smaller amounts of insulin, the 0.7 - 1.5 unit increase in insulin on ascent will peak 60 - 90 minutes and can be quite a devastating experience. It would not surprise me if this was a fatal experience for some.

My situation, in both flights the hypoglycemia, was amplified by the fact that I had bolused for food, so the bolus and the existing basal BOTH created excess insulin on the ascent that the decrease in descent was not sufficient enough to remedy.

As I cannot disconnect from the Omnipod, I am not confident that suspending the pump while ascending or descending will change the fact that air pressure has affected the pump (like the water bottle). I can’t push the excess insulin out of the system without it going into my system and I fear that the changes to air pressure would be realized when the Omnipod is turned back on after landing.

As that is the case, and as I can’t find any evidence to disprove this, I have chosen to go on Lantus during the days when I fly and a pen needle with short-acting insulin to cover my food intake during that time.

I still take all of my pump supplies with me and go back on the pump 12 hours after landing and when Lantus basal is out of my system. The morning of my return flight, I disconnect from the omnipod and I take Lantus as my 12-hour basal and use the pen needle with my short-acting insulin for food.

Better to be safe than sorry.

2 Likes
15

Super interesting answer, @SophiaMontoya, and welcome to the forum!

1 Like
16

Hi SophiaMontoya,
Welcome to FUD.

About the pump issues on a plane.

For practical purposes, under the conditions we would be exposed to, liquids are not compressible. So their volume does not change appreciably with pressure changes.

So the only thing that can affect the volume of insulin in the pump as altitude changes is if there are air bubbles in the pump’s insulin reservoir. The insulin will not change volume.

Being inside an airplane is not that same as being in the vacuum of space. On typical commercial flights, the interior of the airplane is kept at a pressure equivalent to roughly 6000-8000 feet altitude, which is a minor change for the volume of air at a constant temperature.
(Ideal gas law: PV = nRT, or V = nRT/P for volume)

If a plane takes off from sea-level, the interior pressure would go from 14.7 psi to about 11 psi (depending on interior temp of airplane cabin). (And this would only affect the microscopic air bubbles inside the pump’s reservoir!)

Since the amount of air inside the insulin reservoir is minimal (otherwise you’d have bigger problems) and since the pressure changes inside the plane are minimal, this is really an inconsequential difference. You would probably get a bigger change in the size of the reservoir’s air bubbles by taking a hot shower and heating it up. (using the same formula for Ideal gas law)

Lots of other things to worry about. This isn’t one of them!

2 Likes
17

I find this discussion very interesting. My biggest issue with flying is how sedentary I am during flights. I ALWAYS have to give myself extra insulin during the flight. For longer flights, this may mean several injections just to keep my blood sugar in the range it would normally be. For REALLY long flights, I give myself extra Lantus for that day. I don’t remember how this differed when I was on a pump, but I’ve definitely had to make adjustments since I went on MDI. Seems odd to me that pumpers drop low!!!

18

I would like to believe you but my experience and that of others cannot be completely explained through your analysis. Do you think perhaps some infusion sets, pumps, pods/OmniPod might be somewhat sensitive or defective to cause hypoglycemic events?

Can I ask you where you found the information you posted in the response to my post? Could you post a link? There was no source.

I’m not sure what testing has been made transparent to pump users, but I and many others have had serious lows that occur upon landing and your analysis doesn’t quite address this phenomenon. So something is amiss. I say this in a friendly way as possible. Your post seemed to discount real experiences with your response.

I don’t think that you want to say for certain that serious hypoglycemic events after flights have nothing to do with the changing air pressure on flights for all type 1 diabetics and all pumps.

Real experience, mine and that of others should not be discounted especially when doing so could lead people astray and deny them the opportunity to prepare themselves for dangerous hypo events.

By the way, I have never had a hypoglycemic event after taking a hot shower! I take hot showers daily, so I have lots of experience :slight_smile:

Flying and taking a hot shower do not have the same effect on a pump.

If the reports say they do, then they have not caught up to the many experiences that people have had, and certainly is contrary to this study by the American Diabetes Association: http://care.diabetesjournals.org/content/34/9/1932

I am not sure if you have ever personally experienced a dangerous low after flying and never had dangerous lows otherwise?

I’m not sure if you have had several dangerous lows after flying and never had dangerous lows otherwise. I do know that I have.

And I am not sure if you have also tested with flying under a different regimen, such as using Lantus injected by pen needle, as a comparable experience and found absolutely no problem with lows as I have.

You didn’t suggest that you did, and you discounted the connection, so I am assuming that you don’t have personal experience with this.

Air pressure changes are something to worry about, there is lots of anecdotal experiences disclosed and evidence through scientific study.

AIr pressure changes have caused serious hypoglycemic events, and as such, your response “lots of other things to worry about. This isn’t one of them!” to be inappropriate, contrary to evidence, and contrary to people’s experiences, and generally not helpful to others that have had similar experiences and are searching for solutions and for other people’s events.

I think it is always best to understand that science and testing are always evolving, but peoples experiences are real and often science takes time to catch up to explain what people have experienced.

I ask that you post your response to something this serious without minimizing actual experiences and that you source any information you post as evidence so that people can weigh your analysis.

Your response dismisses the experience I shared, that others have disclosed on diabetes sites similar to fudiabetes, it also served to close off the discussion and to discourage others to share their experience. The opposite effect of the purpose of this site.

Can I encourage you to use this platform to ask people to share their experiences relating to hypoglycemia post flights, ask people to share information from credible sources on the changes of air pressure on pumps and not to discount their experiences, especially without sourcing evidence?

There seems to be a lot of shared experiences regarding hypos post-flight that should be discussed and shared openly so that we (diabetics) and pump manufacturers can learn from.

Best,
SM

1 Like
19

Here’s an interesting article from the National Center for Biotechnology Information (NCBI). Not sure if you’ve read this or not, but it contains some pretty interesting information about what could be occurring (including false positives, trapped air within the ampule/infusion set, among other things.)

Impact of High Altitudes on Glucose Control

And welcome, @SophiaMontoya! Everyone tries to give their best information possible and Eric has been living with Diabetes for over 45 years now so if it can be experienced, I’m pretty sure he’s experienced it! But as always, we’re all learning and growing together, so hopefully, we can put our heads together and figure this out, or at least have some very good ideas of what could be causing this. Please feel free to introduce yourself, and share your story with us!

4 Likes
20

Hi SophiaMontoya,
There are a lot of possibilities for why flying could cause a low. What I was saying is that it is not the pump. Certainly other factors could be involved.

I quoted what is known as Ideal gas law, which is a well-known formula. If you google that you can find it. The other things I referenced is the fact that liquids do not change volume from normal pressure variations. That’s another well-established fact from references in hydrostatics. And the pressure inside the airplane cabin you can also get from google. This topic has come up before.

But to simplify things a bit, let’s put the formulas and fluid dynamics aside for a bit. When people report instances like this, or when parents say their children’s BG dropped on a flight, there are many other things at play.

Not necessarily for your experience, but a common scenario might be someone goes to the airport and they have to park in the lot and walk a distance to the airport carrying their luggage. Then walk through security, then walk to the gate. For someone not used to that exercise, a drop in BG is not surprising.

Or for children, the excitement of a plane flight could make their heart beat faster and that could speed up insulin absorption (in addition to all the walking they do leading up to the flight).

For some people flying makes them nervous, and the stress could make their BG climb.

In your explanation you explain that both times you ate and bolused prior to the low. So there are possibly other things involved.

So what I am saying is - sure the circumstances involved in flying can cause a low. Or a high. But there are a lot of other factors. The pump is not the thing to be worried about.