I had my sleep study last night with my new sleep doctor for a second opinion. Baffling results-

My PCP wrote the order-the sleep tech was somewhat puzzled with the nature of the order.  I had to go to sleep without my CPAP!  I was in dread and wondered how I would even sleep for a few minutes!  Well, I fell asleep (not sure how soon) I woke up about 5 hours later to pee.  I went back to sleep, and the tech woke me up 2 hours later.  She stated I had no significant desaturations! She said that I did not even have enough events to qualify for sleep apnea!  She could tell me nothing else other than, "Your pressure setting of 12 is way too high!" I woke up feeling refreshed!

Now-Could this be another false negative study as was my very first study?  

Or could I possibly have high altitude induced sleep apnea?

or could my providers have failed to reassess and titrate my pressure correctly, given the altitude change and weight loss of 14-15 pounds?

My initial 2 studies done JAN and FEB 2008 were conducted at an altitude of 7200 feet, where I lived for 5 years.   My pressure was titrated to 12 at 7200 feet.  I moved to an elevation of 3200 feet, then noticed the onset of symptom relapse.  I have asked my sleep practitioner on a number of occasions to review my titration, due to change in altitude and weight loss.  She stated no need, and in fact stated "there is no relationship between altitude and sleep apnea."  I strongly disagreed.  

My study last night was done at a different facility 2 hours away, elevation 1000 ft.  I slept without my CPAP, which I never thought possible, and the tech said I did not show as having apnea!  This left me utterly baffled!

Then, as I sat eating breakfast with my son and best friend at Cracker Barrel-a light bulb went on-I may have figured out the answer to this baffling situation.

I decided to look at some mathematical calculations I came up with on my own:  

First, I thought OK my pressure setting is 12/7200 feet=0.0017

Could 0.0017 be the pressure requirement per 1 foot above sea level, multiplied by the number of feet above sea level, to achieve the needed therapeudic affect required to stint my airway open?

Then, I took the 0.0017 and multiplied that x the number of feet elevation where I now live:  0.0017x3200=5.44 or maybe a pressure of 6mm H20 CPAP pressure needed to adjust to this altitude.

Then, I took the 0.0017 and multiplied- 0.0017x1000 (elevation of study last night)=1.7 mm H2O pressure= NO CPAP NEEDED!!!


I understand that CPAP titrations range from 4-24, respectively.  1.7 is <4-WHICH WOULD INDICATE NO NEED FOR CPAP!

I would think that a pressure setting too high could actually cause sleep apnea/central sleep apnea, as well as a reduction in oxygen saturation levels.  This would explain why I did so well the first 2 months, have relapsed the past 2-3 months, and showed being void of problems at an elevation of 1000 feet last night!  


I decreased my altitude by about 50-55%, where I now live.  The mathematical equasions I came up with show that if my hypothesis could be correct, I would require a pressure reduction of 50-55%!!  I would go from 12 down to 6!  


I just spoke with my father who has a friend with OSA, same CPAP as I.  I told them my hypotheses.  My father's friend states THE EXACT same thing happened to him!  He does not know about my specualtions, as it is complex.  The friend stated that someone had failed to properly adjust/titrate his machine for the altitude, and he suffered the same as I.  

HAS ANYONE ELSE HERE HAD A SITUATION SUCH AS THIS?  READ MY PREVIOUS POSTS AND FOLLOW WHAT I HAVE BEEN THROUGH THE PAST FEW MONTHS.  

IS it possible that some people with OSA can experience onset, increase, ordecease of symptoms and severity based upon altitude changes?

It would certainly seem to make sense that a number of variables are considered when titrating pressures. The 0.0017 would possibly apply to individual cases, and that number could change based upon individual variables.  

Please write what you think and share any experiences.  I must wait 2 weeks to hear from the new doctor.  NOT SURE WHAT TO DO IN THE MEANTIME.-Lantern

If it were ME, I would go w/o CPAP! I've read that altitude MUST be taken into account when x amount of feet above sea level. THAT is why these newer CPAPs usually have automatic altitude adjustment and the older ones had instructions on how to adjust them for the higher altitudes.

Or at the very least, reduce my pressure to 5-6 cms and sleep w/it until I could talk to this new sleep doctor. I'd just go by how I feel between now and then at 5-6 cms, you can always raise it 1 cm at a time if needed.

But then, that is what I would do. And I do tend to be on the conservative side when it comes to my therapy and health care. Yes, I push for what I think I need and/or want but I'm not very aggressive when it comes to changing my therapy or my medications or dosages.


_________________
Some people are like Slinkies... Not really good for anything, but they still bring a smile to your face when you push them down a flight of stairs.
Resmed VPAP Auto. Humidaire 3i, Simplicity & Micro masks, ResScan 3.4, S8 ResLink, Embla oximeter.

Conclusions: Because AHI decreases significantly with descent in altitude, polysomnography is most accurately done at the home elevation of the patient. Descent to a sleep laboratory at a lower elevation may yield false-negative results in patients with mild or moderate sleep apnea.

--

From a study I found. ill post the link later. It was the first google hit, I believe.

HI!  Your hypothesis certainly seems right on for YOU.  It's quite a coincidence otherwise.  I would bet that these 3 tests are directly related to the altitude changes...but that still leaves you in a predicament since you don't have an accurate titration for where you live (other than your own deductions I mean).  It will be interesting to see what the dr thinks of your calculations too.

It seems like a 'definite' that you should not continue the cpap at 12.  I guess you could try either none or the 6 and see how you do; whichever yoyu feel more comfortable in trying.  Which ever you choose, you should feel more rested, and be safer than being at the 12 pressure.

keep us posted in what you do and how it works for you.  I'm so glad you've found out the 12 is too much!
take care!

embryopathy wrote:

HI!  Your hypothesis certainly seems right on for YOU.  It's quite a coincidence otherwise.  I would bet that these 3 tests are directly related to the altitude changes...but that still leaves you in a predicament since you don't have an accurate titration for where you live (other than your own deductions I mean).  It will be interesting to see what the dr thinks of your calculations too.

It seems like a 'definite' that you should not continue the cpap at 12.  I guess you could try either none or the 6 and see how you do; whichever yoyu feel more comfortable in trying.  Which ever you choose, you should feel more rested, and be safer than being at the 12 pressure.

keep us posted in what you do and how it works for you.  I'm so glad you've found out the 12 is too much!
take care!

I am not sure that it is a definite that he/she doesnt need 12 cm h20. Its hard to say. Im not trying to nitpick, but instead I wanted to throw out the idea that 12cm h20 is not a matter of OSA severity. Some users need "higher" pressure to correct a mildly high AHI. The problem is that her last sleep study wasnt performed at her sleeping altitude and thus may not have been accurate. It sure seems like a mess!!

Lantern,

I am so very glad you seem to be doing well today and that you might have a possible answer!

Could it be that the CPAP left on the high pressure and then you moving down to a lower altitude triggered a central apnea...making you blue lipped, etc???

Hoping you get some relief,

Neil

Onewaypockets-
Thank you for wishing me well.  Your question reflects EXACTLY what I am wondering! Lantern

Thanks Chronie Too for your input.  I have been thinking of some way to lower my pressure, but HOW? I definitely cannot go without CPAP at 3200feet, as I have already tried and failed.  I would awaken constantly.  Lantern4life


Thank you Embryonopathy-I agree with what you say.

Hi lantern4life

The comment about sleep arcitecure and altitude is interesting.  Following is a link to a paper on the subject mentioned.

http://www.chestjournal.org/cgi/reprint/108/6/1577.pdf

May you find good rest!

Todzo

Better to be somewhat undertreated than way over treated, Lantern. I would either start lowering the pressure by 1 cm a night from the 12 cms OR being the conservative I am when experimenting w/my therapy, I'd be more inclined in this instance to drop the pressure to 5-6 cms and then gradually move it up 1 cm at a time. A third option would be to split the difference and drop the pressure to 9 cms and then go one way or the other from there depending on how you feel and respond.


_________________
Some people are like Slinkies... Not really good for anything, but they still bring a smile to your face when you push them down a flight of stairs.
Resmed VPAP Auto. Humidaire 3i, Simplicity & Micro masks, ResScan 3.4, S8 ResLink, Embla oximeter.

Thank you Todzo-I think this about sums it up!  I am waiting for a definitive answer from my new sleep doctor.Lantern