Central events at altitude

[klmaish]

I spend my summers at 8000'.  After being here a couple of weeks my events climb to around 20.  The software shows around 4 of those are obstructed and the other 16 or so are centrals happening between 4 and 6 am.  

I can't find a sleep doc up here in the mountains nor do I have this problem at low altitudes where my sleep doc works.

Has anyone had this experience?

[Sleeprider]

Increased CA is common at altitude of +8000 MSL. Since you use a fixed pressure Elite, I suggest you self titratrate for high altitude. First step is to turn down EPR to 1 and observe results. If centrals continue above normal for you, reduce pressure until a "normal" AHI is achieved. You may need to compromise OA and CA events. Go for the best results fine-tuning pressure in small increments. This will be your new high altitude setting. Next time you renew your prescription, ask for auto CPAP (Autoset) and the machine should do this for you.

If you don't achieve acceptable results, you may have high altitude central apnea. Depending how much time you spend at altitude and resulting impairent, this may be treated with prescribed Diamox, or ASV. We have had members treated for high altitude CA, but getting a dedicated machine pretty much requires that you live at that altitude as opposed to occasional ski trips or weekends.

[klmaish]

Thanks for your prompt response.  I now realize my profile had my old machine.  I now have an autosense 10 which does titrate for me.  I've checked EPR.  I don't have number settings just on and off.  It was on, I'll try off. 

 Finally I do live here for about 4 months in the summer.  The odd thing....sometimes I'm good at about 3.5 events and sometimes I go up to 20.  From Sleepyhead, it appears the difference is all Centrals between 4 and 6 am.

Any help is appreciated.

[Sleeprider]

EPR can be set on or off, Full time or Ramp only and if on to a setting of 1, 2 or 3. If you were to post a Sleephead chart we could sort out what's going on pretty quickly. Instructions for organizing and posting are in my signature.

Basically at higher altitude you may have a lower pressure need. The trick is to maintain airway patency to avoid obstruction, but not over ventilate and lose CO2 as a result of the slightly higher respiration rate that you may naturally have at high altitude to compensate for lower oxygen partial pressure. There is another way to approach high altitude central sleep apnea that is very promising and requires some McGyver ingenuity to solve. You may be just the guy. A technique called Enhanced Expiratory Rebreathing Space (EERS) creates dead space in the CPAP breathing circuit to preserve CO2 and eliminate the problem of central apnea due to the flushing of CO2. Her is a link to a thread where we are discussing how to construct an EERS by moving the exhalation vent from the mask, to a position closer to the CPAP machine. This allows exhaled air to enter the CPAP hose rather than vent directly, and affords
http://www.apneaboard.com/forums/Thread-...eep?page=2

Since you are the engineering type, maybe you could double check my calculation of rebreathing air dead-space in this post: http://www.apneaboard.com/forums/Thread-...#pid265504

I think EERS may hold the best hope of solving your problem simply, and avoid the need to make any changes in settings. It should also provide a bit more humidity and warmth in the CPAP air at altitude. Let me know if this was understandable or if you would like to discuss it further as a possible solution.

[S.L. Ping Beauty]

Hi klmaish - I won't begin to give machine/ device setting advice on what you should do because there are members here who are more learned than me... but I will relate my experience for living with CPAP at almost 10,00 feet:

For the first year I was on CPAP (I forget the numbers) and EPR off and it was not a good fit for me. For the next 8 months (as well as currently) my doctor changed me to APAP with a range of 6-14 and EPR on.

These new settings for me have made a world of difference in a huge way. I am not recommending that you do the same, only relating for example of changing settings (once you find out what is right for you) can be a good thing..

[klmaish]

Thanks for relating your experience.  I appreciate it!

[klmaish]

So I'm attaching two images, one I call a "good day" where AHI is around 8 and one I call a "bad day" where it is over 20.   I noticed that darkening the room last night helped but I don't know if this is a coincidence.

As always, your input is appreciated.

[Sleeprider]

It would help us to see more useful data if you minimize the monthly calendar by clicking the triangle in the date line, and turn off the pie chart of events in the menu, File/Preferences/Appearance (uncheck Show Event Breakdown Pie Chart).  Making these changes will let us see the statistics on pressure and settings.

You clearly have a significant issue with centrals at altitude. It seems to me you may have several options:

• Try lower CPAP pressure at altitude.
  
• Request a prescription for Diamox and start taking that several days before going to altitude.  
  
• Build an EERS to help increase CO2 retention and prevent centrals.  
  
• Avoid high altitude.  
  
• Live with it.  
  
• Obtain a ASV unit for use at altitude (expensive option).
  

I think your pressure settings are near what you need to avoid obstructive apnea, but for high altitude I would set the range to 8.0 minimum and 10.0 maximum and see if that helps.

[klmaish]

Thanks.   It's curious that my sleep doc said to INCREASE the pressure at altitude and you say decrease it.   I guess you both could be right....increasing it takes care of obstructive events but apparently creates centrals. 

I'm kinda stuck now because my sleep doc won't talk to me unless I go into the office and it is 250 miles away. I think the doc could come into the 21st century as he/she has access to my data online.  Anyway, here're the latest screenshots.

[Sleeprider]

Those graphs are much better and let us know more of what the machine is doing. I really think an EERS modification would resolve this problem, but not everyone is handy enough to do it. Increasing pressure is a pretty standard response for obstructive apnea, but can make centrals worse as you note. You are not alone in this problem, and studies have documented that reductions in altitude reduces central apnea and hypopnea, but not obstructive apnea https://www.ncbi.nlm.nih.gov/pubmed/17166991

I think full acclimation to high altitude can take months. While doctors seem to be aware of the prevalence of central and mixed apnea at high elevation, there is very little research that can guide them on how to address it. Some will suggest supplemental oxygen, your doctor thinks higher pressure is the answer. The root cause is the the faster or deeper breathing you naturally do when the oxygen level is lower causes a lower CO2 level which is reduces respiratory drive. Compare your low-altitude respiration rate and tidal volume with the high altitude, and I think you will see a difference. I'm surprised there are not more doctors and clinics in Colorado that specialize in this problem.