AHI very strange

[bucko]

I have been struggling to get my AHI under control for over a year now. I finally can get it to hover around 8, which is "as good as it gets". I know about leaks, hose management, etc, so please don't go there on this thread. There is something more to the reason I am posting this.

I just spent a month in Phuket (sea level). From the first night there my AHI was 3. For the entire month it never got higher than 4. EVERYTHING is exactly the same, except that I went from my home (7000 ft elevation) to living at sea level. This is the ONLY change that I can relate these numbers to. Also I have slept 1.5 to 2 hours a night longer as well.

I thought my equipment was automatically compensating for altitude, but I suspect this is not working, or I don't have some magic secret switch set right. Anybody have an idea here? Please comment.......

[jdm2857]

You did not say how you felt. Did you feel better with the lower AHI?

And if you suspect that your machine is not compensating, why now tweak your pressure upwards and see what happens?

[socalmonkey]

There is not a magic switch. It's suppose to auto adjust for altitude. You might want to take it to your local DME and have the calibration checked.

When you went back home, did your AHI go back up? I'm not sure if you mentioned that in your post. Maybe your still at sea level.

[Wulfman]

Bucko,

How is your machine configured? (pressure settings, etc.)

They ARE supposed to adjust for altitude, however you might be close to the upper limits at 7000 ft.


Den

[kteague]

Since we're on the subject, are any machines particularly better for use at higher altitudes? Seems I remember an altitude setting on my former ResMed.
Kathy

[Wulfman]

Since we're on the subject, are any machines particularly better for use at higher altitudes? Seems I remember an altitude setting on my former ResMed.
Kathy

As far as I know, all full-data-recording machines have auto altitude adjustments. The others have manual altitude adjustments.
I don't think any of them are any "better". At some point, when the upper altitude limit has been reached, adding 1 or 1 1/2 cm. per 1000 ft. is supposed to compensate for that. (from what I've read)
I think it would be advantageous to run an Auto machine in CPAP mode at higher altitudes rather than trusting them to compensate in a range of pressures.


Den

[mars]

Hi Bucko

What does your manual say about altitude? Have you contacted the maker of your machine and asked about the altitude you are usually in, and the machines ability to compensate for it.

If your current machine does not compensate for the altitude, you might want to -

check out other manufacturers (I only know the Sandman Auto - altitude range 0 - 9000 feet, in the user manual)

other forum members living at 7000 feet. What is their experience.

As you say - the significance is too great to ignore.

Good luck.

cheers

Mars

[bucko]

I am using my CPAP on C-Flex mode and it is set at 10~15 cm. I have not changed anything at either location. Not even the humidifier setting.

The machine is barely a year old, and this is the first time I took it traveling because I would be staying away for so long. I am back using it at home (7000 ft) and 8 is the lowest AHI. It is more averaging 15 AHI.

How about another question that comes to mind. Maybe the sensors that read this data to the card are effected by altitude, and it is the readings that are wrong. Maybe my AHI hasen't changed at all. Is that possible?

I can't say I noticed feeling any different., but I did sleep more hours a night at sea level. Normally I only sleep 5.5 hours a night, and in Phuket I alomst sleeping 7 hrs a night. I've never done that in 20 years.

[bobkat13]

Well......first of all: was Phuket time vacation time? I spent a week there in July 1998 and it was a wonderful vacation! We stayed at the Boathouse. It's not normally their "high season" in the summer, but we were living in Pakistan at the time and Thailand wasn't any steamier than Pakistan was, so it was still a vacation.

Vacation time may mean you're relaxing more....

I'm thinking that if your data is accurate, then you're not getting the treatment you really need at 7000 feet. Sorta one of those "walks like a duck, quacks like a duck" situations.

[Wulfman]

I am using my CPAP on C-Flex mode and it is set at 10~15 cm. I have not changed anything at either location. Not even the humidifier setting.

The machine is barely a year old, and this is the first time I took it traveling because I would be staying away for so long. I am back using it at home (7000 ft) and 8 is the lowest AHI. It is more averaging 15 AHI.

How about another question that comes to mind. Maybe the sensors that read this data to the card are effected by altitude, and it is the readings that are wrong. Maybe my AHI hasen't changed at all. Is that possible?

I can't say I noticed feeling any different., but I did sleep more hours a night at sea level. Normally I only sleep 5.5 hours a night, and in Phuket I alomst sleeping 7 hrs a night. I've never done that in 20 years.

Did you ever consider that you may not have your minimum pressure high enough to begin with?
Or......trying CPAP (single-pressure) mode?

Also, you didn't say what your humidifier setting was, but a number of people on the forum have reported that their AHI dropped when they went to "passover" humidification (no heat or "Off").


Den

[Raj]

There's a bit more oxygen in the air nearer sea level. Other factors might be the bed and pillow you used plus any change in your hose management. Small differences in posture, neck position, and hose position can make a big difference in breathing.

[turbosnore]

The manual for REMstar Auto M Series says that the upper limit for altitude compensation is 7500 ft.
I guess it doesn't work so well at those hights. Maybe the altitude compensation is set fixed in your machine?
(Is it possible?)

Does anybody know how the altitude compensation affects the machine?
The air pressure - of course - changes, but it's hydrostatic pressure: the pressure of air in the
nose is pretty much the same as the pressure outside the chest. The breathing pressure difference
(underpressure in the lungs) is probably quite the same.

[jdm2857]

Remember that xPAP pressure is supposed to support collapsed upper airway structures, which collapse due to gravity, not external atmospheric pressure.

That said, I wonder if OSA would disappear in zero gravity conditions, as on the space station. Not that NASA would let anyone with OSA fly.

[rested gal]

I wonder if OSA would disappear in zero gravity conditions, as on the space station.

Yep.

Not that NASA would let anyone with OSA fly.

Oh, but they do....

2001-09-04 | SCIENCE "Sleeping Soundly in Space"
Two studies performed on astronauts indicate that sleeping in the absence of gravity reduces certain sleep-disturbing conditions common on Earth. In the studies, astronauts in orbit stopped snoring and experienced fewer occurrences of disruptive breathing patterns such as apnea, a condition where sleep is interrupted by a termination of breathing; and hypopnea, a condition where normal breathing is reduced, producing long, shallow breaths. These conditions effect millions of people in America alone. Thes studies are the first proof that gravity does indeed play a role in these conditions.


"Sleep Better in Space"
By Heather Sparks
Staff Writer
24 August 2001

Space travel enthusiasts promise adventure, out-of-this-world views and bouncy antigravity rooms, but scientists have now found another selling point for interstellar R&R: Humans sleep in space more soundly than on Earth.

During a study of two 1998 space flights, five astronauts stopped snoring almost completely. The astronauts also experienced a significant decrease in sleep-disturbing periods of breathing cessation, called sleep apnea, as well as periods of slow and shallow breathing called hypopnea.

Scientists from the University of California, San Diego, Brigham and Women's Hospital, and NASA Ames Research Center published the research in this month's issue of the American Journal of Respiratory and Critical Care Medicine.

[jdm2857]

I always thought that NASA's strict health requirements for astronauts would eliminate any chance of an astronaut with OSA.

And to heck with CPAP, we need anti-gravity machines!

Is there an insurance code for them?