Elevation Effects on Sleep Apnea

[AirBreather]

I have used CPAP or APAP for almost 20 years. In recent years I have used a ResMed S9 AutoSet running in AutoSet mode. Most of that was at 5200 feet above mean sea level. My sleep had become increasingly poor in recent years at that altitude, fragmented at best, and often very poor. Of course, I felt awful most days because of that.

Eight months ago I moved to sea level on the Oregon Coast. That move was not made with the hope of improving my sleep. I didn't expect moving to sea level would have much effect on my sleep, because, after all, I was using a machine that provided Continuous Positive Airway Pressure automatically adjusted to meet my varying needs. At least that is what I had thought it was doing.

The first night at sea level I slept seven hours straight through without waking up. That had almost never happened in recent years at 5200 feet. The same thing happened the second night, the third, the fourth, and most nights since, except during trips back to high elevation to visit family and friends.

ResScan plots show that the machine does adjust treatment pressures in attempts to compensate for reduced air pressures at high altitudes, but the needed compensation exceeds the maximum practical adjustment range due to mask leakage. I often need more than 15 cmH20 at 5200 feet to avoid obstructive apneas. Mask leaks keep the machine from being able to raise the treatment pressure much above that, which makes treatment at that altitude ineffective. The leak problem could be reduced with a full-face mask, but I sleep even worse with a full-face mask, because it is so extremely uncomfortable.

The solution was to move to sea-level, but I hadn't known that before moving. I moved for other reasons (primarily because the Oregon Coast is one of the most beautiful places on earth), but would have moved years sooner had I known what I know now. Sleeping all night, night after night, has had enormous positive effects on how I feel and what I am consequently able to accomplish and enjoy.

It could be argued that something else may have caused the sleeping difference. However, each time I go back to high altitude, the same thing happens, which convinces me that the best place for me to live is here on the Coast at sea-level breathing some of the cleanest air on the planet blowing in off the Pacific Ocean.

You can view a ResScan treatment pressure bar-chart by taking the link below that shows ResMed S9 AutoSet pressure changes during a recent short road trip from sea-level to high elevation and back. The dotted line pressure is 15 cmH20. These are the elevations I was sleeping at each night:

Day 1: Sea Level
Day 2: 850 Feet
Day 3: 4200 Feet
Day 4: 4200 Feet
Day 5: 5200 Feet
Day 6: Sea Level
Day 7: Sea Level

Sea-Level vs. Elevation Bar-Chart

My experience with this suggests two things. 1) People with significant sleeping problems at a high elevation should experimentally try sleeping a few nights at or near sea level. 2) Anyone using CPAP who now lives at a significantly different elevation than the elevation where their sleep study was performed probably should have a new study to be sure their machine settings are optimum.

I am not a physician and am not intending to give medical advice. I am just reporting my own results and what they mean to me.

[DreamStalker]

Couldn't help but notice that you use a nasal mask.

The net pressure difference between your CPAP respiratory environment and the exterior ambient environment is differnet at your mile-high location than your sea level location.

So it begs the question, do you use a chin strap or tape to make certain that you're not mouth leaking a mile above sea level?

[avi123]

There are two issues here.

1) The XPAP adjustment to different elevations. As I understand it, most newer XPAPs (including the Resmed S9 line) do adjust to elevations atmospheric pressures.
Otherwise the setting on the XPAP need be done manually. The aim is to deliver to the person the same amount of Oxygen per minute of NORMAl XPAP respiration.

2) A person's respiration could be sensitive to elevations. For example, a person suffering from Periodic Breathing would be effected at higher elevation more than one without this medical condition.

[cqfd93]

My average AHI is exactly the same where I live (at 200 ft above sea level) and over a 19 day stay at 5500 ft.
The only differences I noticed are lower pressures and tidal volumes when I'm at 5500 ft.

[AirBreather]

Couldn't help but notice that you use a nasal mask.

The net pressure difference between your CPAP respiratory environment and the exterior ambient environment is differnet at your mile-high location than your sea level location.

So it begs the question, do you use a chin strap or tape to make certain that you're not mouth leaking a mile above sea level?

Yes, I use a chin strap.

[AirBreather]

There are two issues here.

1) The XPAP adjustment to different elevations. As I understand it, most newer XPAPs (including the Resmed S9 line) do adjust to elevations atmospheric pressures.
Otherwise the setting on the XPAP need be done manually. The aim is to deliver to the person the same amount of Oxygen per minute of NORMAl XPAP respiration.

My S9 does adjust with elevation changes. The problem results from the entire system, S9, tubing, and mask, not being able to deliver sufficient pressure at high elevations due to increased leakage as the differential pressure between the CPAP respiratory environment and the exterior ambient environment increases at high elevation.

2) A person's respiration could be sensitive to elevations. For example, a person suffering from Periodic Breathing would be effected at higher elevation more than one without this medical condition.

That would be true without CPAP, but not if a CPAP system is able to maintain the same respiratory environment at high elevation as at sea level. (Assuming that breathing rarefied air during the day didn't cause breathing differences during CPAP treatment at night.)

[AirBreather]

My average AHI is exactly the same where I live (at 200 ft above sea level) and over a 19 day stay at 5500 ft.
The only differences I noticed are lower pressures and tidal volumes when I'm at 5500 ft.

The absolute CPAP respiratory environment pressure could be lower at high elevation due to increased leakage, but the differential pressure between the CPAP respiratory environment and the ambient environment will be higher if your machine properly compensates for air pressure differences with elevation.

If a CPAP system was able to fully compensate for ambient pressure changes a user wouldn't experience any breathing differences with changes in elevation, because the respiratory environment would be identical at any elevation. (Assuming that the ambient pressure didn't drop low enough that external pressure on the chest cavity became a significant factor.)

[chunkyfrog]

I get the same results at 1300 as at 5200.
--comparing with nasal pillows both ways.

[AirBreather]

I get the same results at 1300 as at 5200.
--comparing with nasal pillows both ways.

That probably is due to having very little leakage. Maybe I should try SleepWeaver elan.

[cqfd93]

Back for a two month vacation at 5500 ft, I just spent my first night, very little leakage and again, the tidal volumes (max, 90%, median) dropped by more than 10%.

[Todzo]

I have used CPAP or APAP for almost 20 years. In recent years I have used a ResMed S9 AutoSet running in AutoSet mode. Most of that was at 5200 feet above mean sea level. My sleep had become increasingly poor in recent years at that altitude, fragmented at best, and often very poor. Of course, I felt awful most days because of that.

Eight months ago I moved to sea level on the Oregon Coast. That move was not made with the hope of improving my sleep. I didn't expect moving to sea level would have much effect on my sleep, because, after all, I was using a machine that provided Continuous Positive Airway Pressure automatically adjusted to meet my varying needs. At least that is what I had thought it was doing.

The first night at sea level I slept seven hours straight through without waking up. That had almost never happened in recent years at 5200 feet. The same thing happened the second night, the third, the fourth, and most nights since, except during trips back to high elevation to visit family and friends.

ResScan plots show that the machine does adjust treatment pressures in attempts to compensate for reduced air pressures at high altitudes, but the needed compensation exceeds the maximum practical adjustment range due to mask leakage. I often need more than 15 cmH20 at 5200 feet to avoid obstructive apneas. Mask leaks keep the machine from being able to raise the treatment pressure much above that, which makes treatment at that altitude ineffective. The leak problem could be reduced with a full-face mask, but I sleep even worse with a full-face mask, because it is so extremely uncomfortable.

The solution was to move to sea-level, but I hadn't known that before moving. I moved for other reasons (primarily because the Oregon Coast is one of the most beautiful places on earth), but would have moved years sooner had I known what I know now. Sleeping all night, night after night, has had enormous positive effects on how I feel and what I am consequently able to accomplish and enjoy.

It could be argued that something else may have caused the sleeping difference. However, each time I go back to high altitude, the same thing happens, which convinces me that the best place for me to live is here on the Coast at sea-level breathing some of the cleanest air on the planet blowing in off the Pacific Ocean.

You can view a ResScan treatment pressure bar-chart by taking the link below that shows ResMed S9 AutoSet pressure changes during a recent short road trip from sea-level to high elevation and back. The dotted line pressure is 15 cmH20. These are the elevations I was sleeping at each night:

Day 1: Sea Level
Day 2: 850 Feet
Day 3: 4200 Feet
Day 4: 4200 Feet
Day 5: 5200 Feet
Day 6: Sea Level
Day 7: Sea Level

Sea-Level vs. Elevation Bar-Chart

My experience with this suggests two things. 1) People with significant sleeping problems at a high elevation should experimentally try sleeping a few nights at or near sea level. 2) Anyone using CPAP who now lives at a significantly different elevation than the elevation where their sleep study was performed probably should have a new study to be sure their machine settings are optimum.

I am not a physician and am not intending to give medical advice. I am just reporting my own results and what they mean to me.

Hi AirBreather!

I am not supprised. Sleep apnea stands on two legs, I think. One which everyone sees (the apneas and hypopneas) and one which few see - unstable breathing. I recall reading a study where they attached breathing analysis equipment to those going immediately to high altitude. They all had central apneas. Why, well basically thier chemoreflexes (breathing drive reflexes) were not calibrated to having so little oxygen in each breath of the thin air up there - so they occasionally went into overdrive which wakes them up a bit and then they adjust by not breathing for a spell. I also remeber reading about several studies where oxygen supplimentation reduced or cured central apnea in many. Please note that this kind of hypocapnic central apnea is brought on by "breathing overdrive" which may not be severe enough to actually result in central apneas but will likely result in arousals and sleep fragmentation - I think this is a likely cause of your fragmented sleep at the higher altitude.

When you moved to the lower altitude - well now - that makes each breath contain considerably more O2 - like what you would get if you supplimented at the higher altitude where the air is so much thinner. So breathing is quieted and less likely to become unstable.

What I really would like to encourage for all is constant monitoring of your PAP data. With the flow data and software that would note the changes in minute volume and respiratory rate you could have found this years ago - slept better - and likely conqured the world by this time. I hate the way this disease dulls us down, indeed!!

Glad you have better sleep!

Todzo

[AirBreather]

I am not supprised. Sleep apnea stands on two legs, I think. One which everyone sees (the apneas and hypopneas) and one which few see - unstable breathing. I recall reading a study where they attached breathing analysis equipment to those going immediately to high altitude. They all had central apneas. ...

Thanks for your insight about this. I hadn't read anything about that before.